多铁性材料微结构的电子显微学研究
|
摘要
多铁性材料是材料科学领域与凝聚态物理领域的研究热点，它在存储器、传感器、自旋电子器件中都有着广泛的应用前景。众所周知，材料的性能取决于材料的结构，为了理解多铁性材料的新颖性能并探寻其背后的机制，对于多铁性材料微结构的研究至关重要。本文综合运用电子显微学中的各项技术，对几类重要的多铁性材料的微结构进行了研究。
首先，运用球差校正电子显微术，我们实现了从原子尺度上对六方锰氧化物YMnO_3单晶的拓扑涡旋畴结构进行研究。通过分析类涡旋状的畴结构以及关于涡旋性的探讨，我们指出，仅仅鉴别出6瓣铁电畴并不是确认该涡旋状花样为严格的涡旋的充分条件，对畴之间的反相关系还需要进行仔细确认。通过图像的定量精细研究，我们还可以从中获取材料的局域铁电偶极分布。结合原子模拟计算，我们进一步揭示了两类互锁畴壁的原子构型。
其次，我们分别对六方、正交结构锰氧化物外延薄膜的微结构进行研究。对六方HoMnO_3薄膜的微结构研究指出薄膜中的主要缺陷为异相边界，其形成机制为表面台阶机制与形核层机制。薄膜缺陷处会出现化学计量比失衡，高能电子束辐照会对HoMnO_3的电子结构产生影响。对外延稳定正交TmMnO_3薄膜的微结构研究指出，薄膜中的主要缺陷为界面失配位错，外延应变由界面失配位错和表面起伏机制来共同松弛。
再次，我们对La、Ti共掺杂BiFeO_3外延薄膜的微结构进行了研究。La、Ti的掺杂并没有改变BiFeO_3的晶体结构，掺杂使得薄膜漏电流减少的同时铁电性得到增强。我们讨论了薄膜微结构与漏电流之间的关系，漏电流主要受薄膜内部各种类型的缺陷以及化学成分起伏的影响，其主导机制为体限制Poole-Frenkel发射。
最后，我们对Pb(Mg_(1/3)Nb_(2/3))_(1-x)Ti_xO_3（PMN-PT）基复合多铁性材料的微结构进行了研究。对YBa_2Cu_3O_(7-δ)/PMN-PT的研究表明，YBa_2Cu_3O_(7-δ)薄膜中的主要缺陷是界面失配位错和面缺陷，少量a轴取向畴存在于薄膜中，一些取向畴根部存在微小第二相颗粒，我们讨论了取向畴倾斜畴壁的形成机制，它是表面弹性能与畴壁能相互竞争作用的结果。对Pr_(0.6)Ca_(0.4)MnO_3/PMN-PT的研究表明，薄膜内部具有多取向畴结构。对反相畴壁的原子尺度表征指出不同的畴壁形貌本质上都是由单根直线型反相畴壁基本单元组成。另外，随着膜厚的增加，薄膜中的取向畴增多，有利于电场对Pr_(0.6)Ca_(0.4)MnO_3相分离的调控。
Multiferroics is a hot topic in both materials science and condensed matterphysics, which has extensive applications in storages, sensors, and spintronicdevices. As materials’ properties are determined by their structures, in order tounderstand the novel properties of multiferroics and the mechanisms involved, itis of vital importance to study the microstructures of multiferroics. In this thesis,the microstructures of several important multiferroics are studied by usingdifferent kinds of techniques of electron microscopy.
Firstly, atomic-scale study of topological vortex-like domain pattern inhexagonal manganite YMnO_3single crystals was carried out by usingCS-corrected transmission electron microscopy. The domain configurationshown here was confirmed to be different from a real vortex and thevortex-related issue was discussed. We pointed out that distinguishing of si_xferroelectric domains in the vortex-like pattern was not the sufficient conditionto determine whether this pattern was a real vortex or not. The antiphaserelationship must be carefully checked. Local ferroelectric dipole distributionwas provided by quantitative image analysis. Moreover, atomic configurationsof two kinds of interlocked domain walls were revealed with the help ofatomistic simulation.
Secondly, the microstructures of hexagonal and orthorhombic manganiteepitaxial thin films were studied, respectively. The microstructural study ofhexagonal HoMnO_3thin films indicated that major defects in the films wereout-of-phase boundaries and their formation mechanisms were ascribed to thesurface step mechanism and the nucleation layer mechanism. The defects wereoff-stoichiometric and electronic structure of HoMnO_3was affected byhigh-energy electron beam irradiation. On the other hand, microstructural studyof epitaxial stabilized orthorhombic TmMnO_3thin films indicated that majordefects in the films were interfacial misfit dislocations. Epitaxial strain in thefilms was relaxed by misfit dislocations as well as surface fluctuations.
Thirdly, the microstructure of La-and Ti-codoped BiFeO_3epitaxial thinfilms was characterized. It was found that La-and Ti-codoping can reduce the leakage current and improve ferroelectric behavior of BiFeO_3without changingits crystal structure. The correlation of microstructure with leakage current wasdiscussed. The leakage problem was found to be caused by different kinds ofdefects and chemical inhomogeneities in the films and the leakage mechanismwas dominated by bulk-limited Poole-Frenkel emission.
Finally, the microstructures of Pb(Mg_(1/3)Nb_(2/3))_(1-x)Ti_xO_3(PMN-PT) basedmultiferroic composites were revealed. The microstructural study ofYBa_2Cu_3O_(7-δ)/PMN-PT indicated that major defects in the films were interfacial misfitdislocations and planar defects. Moreover, a small amount of a-axis oriented domainsexisted and in some cases tiny precipitates were observed. The formation mechanism ofthe inclined domain walls was discussed. It was a consequence of competition betweenthe surface elastic energy and the domain wall energy. The microstructural study ofPr_(0.6)Ca_(0.4)MnO_3/PMN-PT indicated that many oriented domains existed in the films.Atomic-scale characterization of the anti-phase boundaries pointed out that all thedomain walls were consist of single-line anti-phase boundary units regardless of theirdifferent apparent morphologies. In addition, the number of the oriented domainsincreased with the increase of thickness of the thin films, which was in favor of themanipulation of phase separation in Pr_(0.6)Ca_(0.4)MnO_3.
首先，运用球差校正电子显微术，我们实现了从原子尺度上对六方锰氧化物YMnO_3单晶的拓扑涡旋畴结构进行研究。通过分析类涡旋状的畴结构以及关于涡旋性的探讨，我们指出，仅仅鉴别出6瓣铁电畴并不是确认该涡旋状花样为严格的涡旋的充分条件，对畴之间的反相关系还需要进行仔细确认。通过图像的定量精细研究，我们还可以从中获取材料的局域铁电偶极分布。结合原子模拟计算，我们进一步揭示了两类互锁畴壁的原子构型。
其次，我们分别对六方、正交结构锰氧化物外延薄膜的微结构进行研究。对六方HoMnO_3薄膜的微结构研究指出薄膜中的主要缺陷为异相边界，其形成机制为表面台阶机制与形核层机制。薄膜缺陷处会出现化学计量比失衡，高能电子束辐照会对HoMnO_3的电子结构产生影响。对外延稳定正交TmMnO_3薄膜的微结构研究指出，薄膜中的主要缺陷为界面失配位错，外延应变由界面失配位错和表面起伏机制来共同松弛。
再次，我们对La、Ti共掺杂BiFeO_3外延薄膜的微结构进行了研究。La、Ti的掺杂并没有改变BiFeO_3的晶体结构，掺杂使得薄膜漏电流减少的同时铁电性得到增强。我们讨论了薄膜微结构与漏电流之间的关系，漏电流主要受薄膜内部各种类型的缺陷以及化学成分起伏的影响，其主导机制为体限制Poole-Frenkel发射。
最后，我们对Pb(Mg_(1/3)Nb_(2/3))_(1-x)Ti_xO_3（PMN-PT）基复合多铁性材料的微结构进行了研究。对YBa_2Cu_3O_(7-δ)/PMN-PT的研究表明，YBa_2Cu_3O_(7-δ)薄膜中的主要缺陷是界面失配位错和面缺陷，少量a轴取向畴存在于薄膜中，一些取向畴根部存在微小第二相颗粒，我们讨论了取向畴倾斜畴壁的形成机制，它是表面弹性能与畴壁能相互竞争作用的结果。对Pr_(0.6)Ca_(0.4)MnO_3/PMN-PT的研究表明，薄膜内部具有多取向畴结构。对反相畴壁的原子尺度表征指出不同的畴壁形貌本质上都是由单根直线型反相畴壁基本单元组成。另外，随着膜厚的增加，薄膜中的取向畴增多，有利于电场对Pr_(0.6)Ca_(0.4)MnO_3相分离的调控。
Multiferroics is a hot topic in both materials science and condensed matterphysics, which has extensive applications in storages, sensors, and spintronicdevices. As materials’ properties are determined by their structures, in order tounderstand the novel properties of multiferroics and the mechanisms involved, itis of vital importance to study the microstructures of multiferroics. In this thesis,the microstructures of several important multiferroics are studied by usingdifferent kinds of techniques of electron microscopy.
Firstly, atomic-scale study of topological vortex-like domain pattern inhexagonal manganite YMnO_3single crystals was carried out by usingCS-corrected transmission electron microscopy. The domain configurationshown here was confirmed to be different from a real vortex and thevortex-related issue was discussed. We pointed out that distinguishing of si_xferroelectric domains in the vortex-like pattern was not the sufficient conditionto determine whether this pattern was a real vortex or not. The antiphaserelationship must be carefully checked. Local ferroelectric dipole distributionwas provided by quantitative image analysis. Moreover, atomic configurationsof two kinds of interlocked domain walls were revealed with the help ofatomistic simulation.
Secondly, the microstructures of hexagonal and orthorhombic manganiteepitaxial thin films were studied, respectively. The microstructural study ofhexagonal HoMnO_3thin films indicated that major defects in the films wereout-of-phase boundaries and their formation mechanisms were ascribed to thesurface step mechanism and the nucleation layer mechanism. The defects wereoff-stoichiometric and electronic structure of HoMnO_3was affected byhigh-energy electron beam irradiation. On the other hand, microstructural studyof epitaxial stabilized orthorhombic TmMnO_3thin films indicated that majordefects in the films were interfacial misfit dislocations. Epitaxial strain in thefilms was relaxed by misfit dislocations as well as surface fluctuations.
Thirdly, the microstructure of La-and Ti-codoped BiFeO_3epitaxial thinfilms was characterized. It was found that La-and Ti-codoping can reduce the leakage current and improve ferroelectric behavior of BiFeO_3without changingits crystal structure. The correlation of microstructure with leakage current wasdiscussed. The leakage problem was found to be caused by different kinds ofdefects and chemical inhomogeneities in the films and the leakage mechanismwas dominated by bulk-limited Poole-Frenkel emission.
Finally, the microstructures of Pb(Mg_(1/3)Nb_(2/3))_(1-x)Ti_xO_3(PMN-PT) basedmultiferroic composites were revealed. The microstructural study ofYBa_2Cu_3O_(7-δ)/PMN-PT indicated that major defects in the films were interfacial misfitdislocations and planar defects. Moreover, a small amount of a-axis oriented domainsexisted and in some cases tiny precipitates were observed. The formation mechanism ofthe inclined domain walls was discussed. It was a consequence of competition betweenthe surface elastic energy and the domain wall energy. The microstructural study ofPr_(0.6)Ca_(0.4)MnO_3/PMN-PT indicated that many oriented domains existed in the films.Atomic-scale characterization of the anti-phase boundaries pointed out that all thedomain walls were consist of single-line anti-phase boundary units regardless of theirdifferent apparent morphologies. In addition, the number of the oriented domainsincreased with the increase of thickness of the thin films, which was in favor of themanipulation of phase separation in Pr_(0.6)Ca_(0.4)MnO_3.
引文
[1] Schmid H. Multi-ferroic magnetoelectrics. Ferroelectrics,1994,162:317-338.
[2] Fiebig M. Revival of the magnetoelectric effect. J Phys D Appl Phys,2005,38:R123-R152.
[3] Eerenstein W, Mathur N D, Scott J F. Multiferroic and magnetoelectric materials.Nature,2006,442:759-765.
[4] Ramesh R, Spaldin N A. Multiferroics: progress and prospects in thin films. NatureMater,2007,6:21-29.
[5] Cheong S W, Mostovoy M. Multiferroics: a magnetic twist for ferroelectricity. NatureMater,2007,6:13-20.
[6] Tokura Y. Multiferroics-toward strong coupling between magnetization andpolarization in a solid. J Magn Magn Mater,2007,310:1145-1150.
[7] Prellier W, Singh M P, Murugavel P. The single-phase multiferroic oxides: from bulkto thin film. J Phys: Condens Matter,2005,17: R803-R832.
[8] Khomskii D I. Multiferroics: Different ways to combine magnetism andferroelectricity. J Magn Magn Mater,2006,306:1-8.
[9] Spaldin N A, Fiebig M. The renaissance of magnetoelectric multiferroics. Science,2005,309:391-392.
[10]王克锋,刘俊明,王雨.单相多铁性材料——极化和磁性序参量的耦合与调控.科学通报,2008,53:1098-1135.
[11]迟振华,靳常青.单相磁电多铁性体研究进展.物理学进展,2007,27:225-238.
[12]何泓材,林元华,南策文.多铁性磁电复合薄膜.科学通报,2008,53:1136-1148.
[13] Curie P. Sur la symétrie dans les phénomenes physiques, symétrie d'un champ électrique et d'un champ magnétique. J Phys,1894,3(Ser. Ⅲ):393-415.
[14] Astrov D N. The magnetoelectric effect in antiferromagnetics. Soviet PhysicsJetp-Ussr,1960,11:708-709.
[15] Tokura Y. Materials science-Multiferroics as quantum electromagnets. Science,2006,312:1481-1482.
[16] Hill N A. Why are there so few magnetic ferroelectrics? J Phys Chem B,2000,104:6694-6709.
[17] Nan C W, Bichurin M I, Dong S X, et al. Multiferroic magnetoelectric composites:Historical perspective, status, and future directions. J Appl Phys,2008,103:031101.
[18] Wang Y, Hu J M, Lin Y H, et al. Multiferroic magnetoelectric compositenanostructures. Npg Asia Materials,2010,2:61-68.
[19] Ma J, Hu J M, Li Z, et al. Recent progress in multiferroic magnetoelectric composites:from bulk to thin films. Adv Mater,2011,23:1062-1087.
[20] Vaz C A F, Hoffman J, Anh C H, et al. Magnetoelectric coupling effects in multiferroiccomplex oxide composite structures. Adv Mater,2010,22:2900-2918.
[21] Atou T, Chiba H, Ohoyama K, et al. Structure determination of ferromagneticperovskite BiMnO3. J Solid State Chem,1999,145:639-642.
[22] Kimura T, Kawamoto S, Yamada I, et al. Magnetocapacitance effect in multiferroicBiMnO3. Phys Rev B,2003,67:180401.
[23] Martin L, Crane S P, Chu Y H, et al. Multiferroics and magnetoelectrics: thin filmsand nanostructures. J Phys: Condens Matter,2008,20:434220.
[24] Graboy I E, Bosak A A, Gorbenko O Y, et al. HREM study of epitaxially stabilizedhexagonal rare earth manganites. Chem Mater,2003,15:2632-2637.
[25] Van Aken B B, Palstra T T M, Filippetti A, et al. The origin of ferroelectricity inmagnetoelectric YMnO3. Nature Mater,2004,3:164-170.
[26] Wang K F, Liu J M, Ren Z F. Multiferroicity: the coupling between magnetic andpolarization orders. Adv Phys,2009,58:321-448.
[27] Lottermoser T, Lonkai T, Amann U, et al. Magnetic phase control by an electric field.Nature,2004,430:541-544.
[28] Rogez G, Viart N, Drillon M. Multiferroic materials: The attractive approach ofmetal-organic frameworks (MOFs). Angew Chem Int Ed,2010,49:1921-1923.
[29] Fabreges X, Petit S, Mirebeau I, et al. Spin-lattice coupling, frustration, and magneticorder in multiferroic RMnO3. Phys Rev Lett,2009,103:067204.
[30] Ren C Y. Atomic, electronic, and ferroelectric properties of manganite RMnO3(R=Ho,Er,Tm,Lu) in hexagonal and orthorhombic phases. Phys Rev B,2009,79:125113.
[31] Kimura T, Goto T, Shintani H, et al. Magnetic control of ferroelectric polarization.Nature,2003,426:55-58.
[32] Yamasaki Y, Sagayama H, Goto T, et al. Electric control of spin helicity in a magneticferroelectric. Phys Rev Lett,2007,98:147204.
[33] Yamasaki Y, Miyasaka S, Kaneko Y, et al. Magnetic reversal of the ferroelectricpolarization in a multiferroic spinel oxide. Phys Rev Lett,2006,96:207204.
[34] Portengen T, Ostreich T, Sham L J. Theory of electronic ferroelectricity. Phys Rev B,1996,54:17452-17463.
[35] Ikeda N, Ohsumi H, Ohwada K, et al. Ferroelectricity from iron valence ordering inthe charge-frustrated system LuFe2O4. Nature,2005,436:1136-1138.
[36] Dagotto E, Hotta T, Moreo A. Colossal magnetoresistant materials: The key role ofphase separation. Phys Rep,2001,344:1-153.
[37] Efremov D V, Van den Brink J, Khomskii D I. Bond-versus site-centred ordering andpossible ferroelectricity in manganites. Nature Mater,2004,3:853-856.
[38] van den Brink J, Khomskii D I. Multiferroicity due to charge ordering. J Phys:Condens Matter,2008,20:434217.
[39] Jooss C, Wu L, Beetz T, et al. Polaron melting and ordering as key mechanisms forcolossal resistance effects in manganites. Proc Natl Acad Sci,2007,104:13597-13602.
[40] Zheng H, Wang J, Lofland S E, et al. Multiferroic BaTiO3-CoFe2O4nanostructures.Science,2004,303:661-663.
[41] Zheng H M, Straub F, Zhan Q, et al. Self-assembled growth of BiFeO3-CoFe2O4nanostructures. Adv Mater,2006,18:2747-2752.
[42] Zheng H, Zhan Q, Zavaliche F, et al. Controlling self-assembled perovskite-spinelnanostructures. Nano Lett,2006,6:1401-1407.
[43] Molegraaf H J A, Hoffman J, Vaz C A F, et al. Magnetoelectric effects in complexoxides with competing ground states. Adv Mater,2009,21:3470-3474.
[44] Thiele C, Doerr K, Bilani O, et al. Influence of strain on the magnetization andmagnetoelectric effect in La0.7A0.3MnO3/PMN-PT(001)(A=Sr,Ca). Phys Rev B,2007,75:054408.
[45]章晓中.电子显微分析.北京：清华大学出版社,2006.
[46]朱静,叶恒强,王仁卉,等.高空间分辨分析电子显微学.北京：科学出版社,1985.
[47]叶恒强,王元明.透射电子显微学进展.北京：科学出版社,2003.
[48] Williams D B, Carter C B. Transmission electron microscopy: A text book formaterials science. New York: Plenum,1996.
[49] Zhan Q, Yu R, Crane S P, et al. Structure and interface chemistry of perovskite-spinelnanocomposite thin films. Appl Phys Lett,2006,89:172902.
[50] Zeches R J, Rossell M D, Zhang J X, et al. A strain-driven morphotropic phaseboundary in BiFeO3. Science,2009,326:977-980.
[51] Borisevich A Y, Chang H J, Huijben M, et al. Suppression of Octahedral Tilts andAssociated Changes in Electronic Properties at Epitaxial Oxide HeterostructureInterfaces. Phys Rev Lett,2010,105:087204.
[52] Zhang J X, He Q, Trassin M, et al. Microscopic origin of the giant ferroelectricpolarization in tetragonal-like BiFeO3. Phys Rev Lett,2011,107:147602.
[53] Zhang J X, Xiang B, He Q, et al. Large field-induced strains in a lead-freepiezoelectric material. Nature Nanotechnol,2011,6:97-101.
[54] Rossell M D, Erni R, Prange M P, et al. Atomic structure of highly strained BiFeO3thin films. Phys Rev Lett,2012,108:047601.
[55] Lubk A, Rossell M D, Seidel J, et al. Evidence of sharp and diffuse domain walls inBiFeO3by means of unit-cell-wise strain and polarization maps obtained with highresolution scanning transmission electron microscopy. Phys Rev Lett,2012,109:047601.
[56] Chen Y B, Katz M B, Pan X Q, et al. Ferroelectric domain structures of epitaxial (001)BiFeO3thin films. Appl Phys Lett,2007,90:072907.
[57] Nelson C T, Winchester B, Zhang Y, et al. Spontaneous vortex nanodomain arrays atferroelectric heterointerfaces. Nano Lett,2011,11:828-834.
[58] Nelson C T, Gao P, Jokisaari J R, et al. Domain dynamics during ferroelectricswitching. Science,2011,334:968-971.
[59] Gao P, Nelson C T, Jokisaari J R, et al. Revealing the role of defects in ferroelectricswitching with atomic resolution. Nature Commun,2011,2:591.
[60] Gao P, Nelson C T, Jokisaari J R, et al. Direct observations of retention failure inferroelectric memories. Adv Mater,2012,24:1106-1110.
[61] Cheng C J, Borisevich A Y, Kan D, et al. Nanoscale structural and chemical propertiesof antipolar clusters in Sm-doped BiFeO3ferroelectric epitaxial thin films. ChemMater,2010,22:2588-2596.
[62] Borisevich A Y, Eliseev E A, Morozovska A N, et al. Atomic-scale evolution ofmodulated phases at the ferroelectric-antiferroelectric morphotropic phase boundarycontrolled by flexoelectric interaction. Nature Commun.,2012,3:775.
[63] Yang H, Chi Z H, Yao L D, et al. Structural defects in multiferroic BiMnO3studied bytransmission electron microscopy and electron energy-loss spectroscopy. J Appl Phys,2006,100:044105.
[64] Bosak A A, Kamenev A A, Graboy I E, et al. Epitaxial phase stabilisation phenomenain rare earth manganites. Thin Solid Films,2001,400:149-153.
[65] Salvador P A, Doan T D, Mercey B, et al. Stabilization of YMnO3in a perovskitestructure as a thin film. Chem Mater,1998,10:2592-2595.
[66] Lee J H, Murugavel P, Ryu H, et al. Epitaxial stabilization of a new multiferroichexagonal phase of TbMnO3thin films. Adv Mater,2006,18:3125-3129.
[67] Jehanathan N, Lebedev O, Gelard I, et al. Structure and defect characterization ofmultiferroic ReMnO3films and multilayers by TEM. Nanotechnology,2010,21:075705.
[68] Han T C, Lin J G. Substrate dependent structure and magnetic properties in HoMnO3films. IEEE Trans Magn,2008,44:2930-2932.
[69] Lin J G, Han T C, Wu C T, et al. Directional growth and characterizations oforthorhombic HoMnO3films. J Cryst Growth,2008,310:3878-3880.
[70] Han T C, Lin J G. Strong coupling of magnetic and dielectric properties in the a-axisoriented orthorhombic HoMnO3films. Appl Phys Lett,2009,94:082502.
[71] Han T C, Chao H H. Observation of large electric polarization in orthorhombicTmMnO3thin films. Appl Phys Lett,2010,97:232902.
[72] Zhang Y, Yang H X, Ma C, et al. Charge-stripe order in the electronic ferroelectricLuFe2O4. Phys Rev Lett,2007,98:247602.
[73] Schattschneider P, Rubino S, Hebert C, et al. Detection of magnetic circular dichroismusing a transmission electron microscope. Nature,2006,441:486-488.
[74] Schattschneider P, Hebert C, Rubino S, et al. Magnetic circular dichroism in EELS:Towards10nm resolution. Ultramicroscopy,2008,108:433-438.
[75] Rubino S, Schattschneider P, Stoger-Pollach M, et al. Energy-loss magnetic chiraldichroism (EMCD): Magnetic chiral dichroism in the electron microscope. J MaterRes,2008,23:2582-2590.
[76] Schattschneider P, Rubino S, Stoeger-Pollach M, et al. Energy loss magnetic chiraldichroism: A new technique for the study of magnetic properties in the electronmicroscope (invited). J Appl Phys,2008,103:07D931.
[77] Lidbaum H, Rusz J, Liebig A, et al. Quantitative magnetic information from reciprocalspace maps in transmission electron microscopy. Phys Rev Lett,2009,102.
[78] Zhang Z H, Wang X F, Xu J B, et al. Evidence of intrinsic ferromagnetism inindividual dilute magnetic semiconducting nanostructures. Nature Nanotechnol,2009,4:523-527.
[79] Wang Z Q, Zhong X Y, Yu R, et al. Quantitative experimental determination ofsite-specific magnetic structures by transmitted electrons. Nature Commun,2013,4:1395.
[80] Uchida M, Onose Y, Matsui Y, et al. Real-space observation of helical spin order.Science,2006,311:359-361.
[81] Zhao T, Scholl A, Zavaliche F, et al. Electrical control of antiferromagnetic domainsin multiferroic BiFeO3films at room temperature. Nature Mater,2006,5:823-829.
[82] Zavaliche F, Yang S Y, Zhao T, et al. Multiferroic BiFeO3films: domain structure andpolarization dynamics. Phase Transit,2006,79:991-1017.
[83] Chu Y H, Martin L W, Holcomb M B, et al. Electric-field control of localferromagnetism using a magnetoelectric multiferroic. Nature Mater,2008,7:478-482.
[84] Seidel J, Martin L W, He Q, et al. Conduction at domain walls in oxide multiferroics.Nature Mater,2009,8:229-234.
[85] Heron J T, Trassin M, Ashraf K, et al. Electric-field-induced magnetization reversal ina ferromagnet-multiferroic heterostructure. Phys Rev Lett,2011,107:217202.
[86] Maksymovych P, Seidel J, Chu Y H, et al. Dynamic conductivity of ferroelectricdomain walls in BiFeO3. Nano Lett,2011,11:1906-1912.
[87] Zavaliche F, Zhao T, Zheng H, et al. Electrically assisted magnetic recording inmultiferroic nanostructures. Nano Lett,2007,7:1586-1590.
[88] Fiebig M, Frohlich D, Lottermoser T, et al. Probing of ferroelectric surface and bulkdomains in RMnO3(R=Y, Ho) by second harmonic generation. Phys Rev B,2002,66:144102.
[89] Lottermoser T, Fiebig M. Magnetoelectric behavior of domain walls in multiferroicHoMnO3. Phys Rev B,2004,70:220407.
[90] Van Aken B B, Rivera J P, Schmid H, et al. Observation of ferrotoroidic domains.Nature,2007,449:702-705.
[91]进藤大辅,平贺贤二.材料评价的高分辨电子显微方法.北京：冶金工业出版社,1998.
[92]王蓉.电子衍射物理教程.北京：冶金工业出版社,2002.
[93] Cowley J M. Diffraction physics.3rd ed. Amsterdam: Elsevier,1995.
[94]李方华.电子晶体学与图像处理.上海：上海科学技术出版社,2009.
[95] Spence J C H. High-resolution electron microscopy.3rd ed. New York: Oxford,2003.
[96] O'Keefe M A, Kilaas R. Adcances in high-resolution image simulation. Scan MicroscSuppl,1988,2:225-244.
[97] Haider M, Uhlemann S, Schwan E, et al. Electron microscopy image enhanced. Nature,1998,392:768-769.
[98] Haider M, Rose H, Uhlemann S, et al. A spherical-aberration-corrected200kVtransmission electron microscope. Ultramicroscopy,1998,75:53-60.
[99] Rose H. Elektronenoptische aplanate. Optik,1971,34:285-311.
[100] Urban K W. Studying atomic structures by aberration-corrected transmission electronmicroscopy. Science,2008,321:506-510.
[101] Jia C L, Lentzen M, Urban K. Atomic-resolution imaging of oxygen in perovskiteceramics. Science,2003,299:870-873.
[102] Houben L, Thust A, Urban K. Atomic-precision determination of the reconstruction ofa90degrees tilt boundary in YBa2Cu3O7-δby aberration corrected HRTEM.Ultramicroscopy,2006,106:200-214.
[103] Jia C L, Mi S B, Urban K, et al. Atomic-scale study of electric dipoles near chargedand uncharged domain walls in ferroelectric films. Nature Mater,2008,7:57-61.
[104] Jia C L, Mi S B, Urban K, et al. Effect of a single dislocation in a heterostructure layeron the local polarization of a ferroelectric layer. Phys Rev Lett,2009,102:117601.
[105] Urban K W. Is science prepared for atomic-resolution electron microscopy? NatureMater,2009,8:260-262.
[106] Jia C L, Urban K W, Alexe M, et al. Direct observation of continuous electric dipolerotation in flux-closure domains in ferroelectric Pb(Zr,Ti)O3. Science,2011,331:1420-1423.
[107] Uhlemann S, Haider M. Residual wave aberrations in the first spherical aberrationcorrected transmission electron microscope. Ultramicroscopy,1998,72:109-119.
[108] Schramm S M, van der Molen S J, Tromp R M. Intrinsic instability ofaberration-corrected electron microscopes. Phys Rev Lett,2012,109:163901.
[109] Muller D A. Structure and bonding at the atomic scale by scanning transmissionelectron microscopy. Nature Mater,2009,8:263-270.
[110] Krivanek O L, Chisholm M F, Nicolosi V, et al. Atom-by-atom structural and chemicalanalysis by annular dark-field electron microscopy. Nature,2010,464:571-574.
[111] Ishikawa R, Okunishi E, Sawada H, et al. Direct imaging of hydrogen atom columns ina crystal by annular bright-field electron microscopy. Nature Mater,2011,10:278-281.
[112] Huang R, Hitosugi T, Findlay S D, et al. Real-time direct observation of Li in LiCoO2cathode material. Appl Phys Lett,2011,98:051913.
[113] Gu L, Zhu C B, Li H, et al. Direct observation of Lithium staging in partiallydelithiated LiFePO4at atomic resolution. J Am Chem Soc,2011,133:4661-4663.
[114] Lu X, Zhao L, He X Q, et al. Lithium storage in Li4Ti5O12spinel: The full staticpicture from electron microscopy. Adv Mater,2012,24:3233-3238.
[115] Egerton R F. Electron energy-loss spectroscopy in the electron microscope.2nd ed.New York: Plenum,1996.
[116]进藤大辅,及川哲夫.材料评价的分析电子显微方法.北京：冶金工业出版社,2001.
[117] Egerton R F. Electron energy-loss spectroscopy in the TEM. Rep Prog Phys,2009,72:016502.
[118] Pearson D H, Ahn C C, Fultz B. White lines and d-electron occupancies for the3d and4d transition metals. Phys Rev B,1993,47:8471-8478.
[119] Cho D Y, Kim J Y, Park B G, et al. Ferroelectricity driven by Y d0-ness withrehybridization in YMnO3. Phys Rev Lett,2007,98:217601.
[120] Zhong C G, Jiang Q, Zhang H, et al. Effect of spin frustration and spin-orbit couplingon the ferroelectric polarization in multiferroic YMnO3. Appl Phys Lett,2009,94:224107.
[121] Kim J, Cho K C, Koo Y M, et al. Y-O hybridization in the ferroelectric transition ofYMnO3. Appl Phys Lett,2009,95:132901.
[122] Oak M A, Lee J H, Jang H M, et al.4d-5p Orbital mixing and asymmetric In4d-O2phybridization in InMnO3: A new bonding mechanism for hexagonal ferroelectricity.Phys Rev Lett,2011,106:047601.
[123] Lee S, Pirogov A, Kang M S, et al. Giant magneto-elastic coupling in multiferroichexagonal manganites. Nature,2008,451:805-808.
[124] Choi T, Horibe Y, Yi H T, et al. Insulating interlocked ferroelectric and structuralantiphase domain walls in multiferroic YMnO3. Nature Mater,2010,9:253-258.
[125] Mostovoy M. Multiferroics: A whirlwind of opportunities. Nature Mater,2010,9:188-190.
[126] Chae S C, Horibe Y, Jeong D Y, et al. Self-organization, condensation, andannihilation of topological vortices and antivortices in a multiferroic. Proc Natl AcadSci,2010,107:21366-21370.
[127] Jungk T, Hoffmann A, Fiebig M, et al. Electrostatic topology of ferroelectric domainsin YMnO3. Appl Phys Lett,2010,97:012904.
[128] Chae S C, Lee N, Horibe Y, et al. Direct observation of the proliferation offerroelectric loop domains and vortex-antivortex pairs. Phys Rev Lett,2012,108:167603.
[129] Geng Y N, Lee N, Choi Y J, et al. Collective magnetism at multiferroic vortex domainwalls. Nano Lett,2012,12:6055-6059.
[130] Wu W D, Guest J R, Horibe Y, et al. Polarization-modulated rectification atferroelectric surfaces. Phys Rev Lett,2010,104:217601.
[131] Wu W D, Horibe Y, Lee N, et al. Conduction of topologically protected chargedferroelectric domain walls. Phys Rev Lett,2012,108:077203.
[132] Meier D, Seidel J, Cano A, et al. Anisotropic conductance at improper ferroelectricdomain walls. Nature Mater,2012,11:284-288.
[133] Safrankova M, Fousek J, Kizaev S A. Domains in ferroelectric YMnO3. Czech J PhysSect B1967,17:559-560.
[134] Chaikin P M, Lubensky T C. Principles of condensed matter physics. Cambridge:Cambridge Univ,1995.
[135] Wang X M, Fan C, Zhao Z Y, et al. Large magnetothermal conductivity of HoMnO3single crystals and its relation to the magnetic-field-induced transitions of magneticstructure. Phys Rev B,2010,82:094405.
[136] Catlow C R A. Solid state chemistry: Techniques. ed. by Cheetham A K, Day P.Oxford: Clarendon,1987.
[137] Catlow C R A. Computer modelling in inorganic crystallography. San Diego:Academic,1997.
[138] Zhang C, Zhang X, Sun Y, et al. Atomistic simulation of Y-site substitution inmultiferroic h-YMnO3. Phys Rev B,2011,83:054104.
[139] Jiang N, Zhang X. Atomistic simulation of Mn-site substitution in multiferroich-YMnO3. J Phys: Condens Matter,2012,24:235402.
[140] Dick B G, Overhauser A W. Theory of the dielectric constants of alkali halide crystals.Phys Rev,1958,112:90-103.
[141] Mott M F, Littleton M J. Conduction in polar crystals. I. Electrolytic conduction insolid salts. Trans Faraday Soc,1938,34:0485-0499.
[142] Gale J D, Rohl A L. The general utility lattice program (GULP). Mol Simulat,2003,29:291-341.
[143] Katsufuji T, Mori S, Masaki M, et al. Dielectric and magnetic anomalies and spinfrustration in hexagonal RMnO3(R=Y, Yb, and Lu). Phys Rev B,2001,64:104419.
[144] Li J, Yang H X, Tian H F, et al. Scanning secondary-electron microscopy onferroelectric domains and domain walls in YMnO3. Appl Phys Lett,2012,100:152903.
[145] Kumagai Y, Spaldin N A. Structural domain walls in polar hexagonal manganites.Nature Commun,2013,4:1540.
[146] Artyukhin S, Delaney K T, Spaldin N A, et al. Landau theory of topological defects inmultiferroic hexagonal manganites.(2012) http://arxiv.org/abs/1204.4126.
[147] Chang H J, Kalinin S V, Morozovska A N, et al. Atomically resolved mapping ofpolarization and electric fields across ferroelectric/oxide interfaces by Z-contrastimaging. Adv Mater,2011,23:2474-2479.
[148] Fong D D, Cionca C, Yacoby Y, et al. Direct structural determination in ultrathinferroelectric films by analysis of synchrotron x-ray scattering measurements. PhysRev B,2005,71:144112.
[149] Zhang Q H, Wang L J, Wei X K, et al. Direct observation of interlocked domain wallsin hexagonal RMnO3(R=Tm, Lu). Phys Rev B,2012,85:020102.
[150] Fujimura N, Ishida T, Yoshimura T, et al. Epitaxially grown YMnO3film: Newcandidate for nonvolatile memory devices. Appl Phys Lett,1996,69:1011-1013.
[151] Murugavel P, Lee J H, Lee D, et al. Physical properties of multiferroic hexagonalHoMnO3thin films. Appl Phys Lett,2007,90:142902.
[152] Lee D, Yoon A, Jang S Y, et al. Giant flexoelectric effect in ferroelectric epitaxial thinfilms. Phys Rev Lett,2011,107:057602.
[153] Laukhin V, Skumryev V, Marti X, et al. Electric-field control of exchange bias inmultiferroic epitaxial heterostructures. Phys Rev Lett,2006,97:227201.
[154] Munoz A, Alonso J A, Martinez-Lope M J, et al. Evolution of the magnetic structureof hexagonal HoMnO3from neutron powder diffraction data. Chem Mater,2001,13:1497-1505.
[155] Horiuchi H, Schultz A J, Leung P C W, et al. Time-of-flight neutron diffraction studyof a single crystal of yttria-stabilized zirconia, Zr(Y)O1.862, at high temperature and inan applied electrical field. Acta Crystallogr B,1984,40:367-372.
[156] Zurbuchen M A, Tian W, Pan X Q, et al. Morphology, structure, and nucleation ofout-of-phase boundaries (OPBs) in epitaxial films of layered oxides. J Mater Res,2007,22:1439-1471.
[157] Gelard I, Jehanathan N, Roussel H, et al. Off-Stoichiometry effects on the crystallineand defect structure of hexagonal manganite REMnO3films (RE=V, Er, Dy). ChemMater,2011,23:1232-1238.
[158] Saterli R. Electronic structure of thermoelectric and ferroelectric materials-advancedtransmission electron microscopy studies[Dotoral thesis]. Norway: Department ofPhysics, Norwegian University of Science and Technology,2010.
[159] Pomjakushin V Y, Kenzelmann M, Donni A, et al. Evidence for large electricpolarization from collinear magnetism in TmMnO3. New Journal of Physics,2009,11:043019.
[160] Feng S M, Chai Y S, Zhu J L, et al. Determination of the intrinsic ferroelectricpolarization in orthorhombic HoMnO3. New Journal of Physics,2010,12:073006.
[161] Brinks H W, Rodriguez-Carvajal J, Fjellvag H, et al. Crystal and magnetic structure oforthorhombic HoMnO3. Phys Rev B,2001,63:094411.
[162] Munoz A, Alonso J A, Casais M T, et al. The magnetic structure of YMnO3perovskiterevisited. J Phys: Condens Matter,2002,14:3285-3294.
[163] Nakamura M, Tokunaga Y, Kawasaki M, et al. Multiferroicity in an orthorhombicYMnO3single-crystal film. Appl Phys Lett,2011,98:082902.
[164] Fontcuberta J, Fina I, Fabrega L, et al. Ferroelectricity and strain effects inorthorhombic YMnO3thin films. Phase Transit,2011,84:555-568.
[165] Marti X, Skumryev V, Laukhin V, et al. Strain-driven noncollinear magnetic orderingin orthorhombic epitaxial YMnO3thin films. J Appl Phys,2010,108:123917.
[166] Marti X, Skumryev V, Ferrater C, et al. Emergence of ferromagnetism inantiferromagnetic TbMnO3by epitaxial strain. Appl Phys Lett,2010,96:222505.
[167] Lin T H, Shih H C, Hsieh C C, et al. Strain-induced effects on antiferromagneticordering and magnetocapacitance in orthorhombic HoMnO3thin films. J Phys:Condens Matter,2009,21:026013.
[168] Marti X, Fina I, Skumryev V, et al. Strain tuned magnetoelectric coupling inorthorhombic YMnO3thin films. Appl Phys Lett,2009,95:142903.
[169]杨军杰.多铁异质结构电、磁特性的调控[博士学位论文].北京：清华大学物理系,2010.
[170] Matthews J W, Blakeslee A E. Defects in epitaxial multilayers.1. Misfit dislocations.J Cryst Growth,1974,27:118-125.
[171] Martin L W, Chu Y H, Ramesh R. Advances in the growth and characterization ofmagnetic, ferroelectric, and multiferroic oxide thin films. Mater Sci Eng R,2010,68:89-133.
[172] Qin Y L, Jia C L, Urban K, et al. Dislocations in SrTiO3thin films grown on LaAlO3substrates. J Mater Res,2002,17:3117-3126.
[173] Suzuki T, Nishi Y, Fujimoto M. Analysis of misfit relaxation in heteroepitaxial BaTiO3thin films. Philos Mag A,1999,79:2461-2483.
[174] Chen Y B, Katz M B, Pan X Q, et al. Microstructure and strain relaxation of epitaxialPrScO3thin films grown on (001) SrTiO3substrates. Appl Phys Lett,2007,91:031902.
[175] Gorbenko O Y, Samoilenkov S V, Graboy I E, et al. Epitaxial stabilization of oxides inthin films. Chem Mater,2002,14:4026-4043.
[176] Li Y, Weatherly G C, Niewczas M. TEM studies of stress relaxation in GaAsN andGaP thin films. Philos Mag,2005,85:3073-3090.
[177] Jonsdottir F. Computation of equilibrium surface fluctuations in strained epitaxialfilms due to interface misfit dislocations. Model Simul Mater Sc,1995,3:503-520.
[178] Wang J, Neaton J B, Zheng H, et al. Epitaxial BiFeO3multiferroic thin filmheterostructures. Science,2003,299:1719-1722.
[179] Choi T, Lee S, Choi Y J, et al. Switchable ferroelectric diode and photovoltaic effectin BiFeO3. Science,2009,324:63-66.
[180] Kim J K, Kim S S, Kim W J, et al. Enhanced ferroelectric properties of Cr-dopedBiFeO3thin films grown by chemical solution deposition. Appl Phys Lett,2006,88:132901.
[181] Wang Y, Nan C W. Enhanced ferroelectricity in Ti-doped multiferroic BiFeO3thinfilms. Appl Phys Lett,2006,89:052903.
[182] Palkar V R, Kumara K G, Malik S K. Observation of room-temperaturemagnetoelectric coupling in pulsed-laser-deposited Bi0.6Tb0.3La0.1FeO3thin films.Appl Phys Lett,2004,84:2856-2858.
[183] Chung C F, Lin J P, Wu J M. Influence of Mn and Nb dopants on electric properties ofchemical-solution-deposited BiFeO3films. Appl Phys Lett,2006,88:242909.
[184] Kim J K, Kim S S, Park M H, et al. Microstructure and electrical properties ofcosubstituted BiFeO3thin films prepared by a chemical solution deposition.Ferroelectrics,2006,345:77-82.
[185] Cui Y F, Zhao Y G, Luo L B, et al. Dielectric, magnetic, and magnetoelectricproperties of La and Ti codoped BiFeO3. Appl Phys Lett,2010,97:222904.
[186] Wu J G, Wang J. Ferroelectric and impedance behavior of La-and Ti-Codoped BiFeO3thin films. J Am Ceram Soc,2010,93:2795-2803.
[187] Brydson R, Sauer H, Engel W, et al. Electron-energy loss and X-ray absorptionspectroscopy of rutile and anatase: A test of structural sensitivity. J Phys: CondensMatter,1989,1:797-812.
[188] Sparrow T G, Williams B G, Rao C N R, et al. L3/L2white-line intensity ratios in theelectron energy-loss spectra of3d transition-metal oxides. Chem Phys Lett,1984,108:547-550.
[189] Pabst G W, Martin L W, Chu Y H, et al. Leakage mechanisms in BiFeO3thin films.Appl Phys Lett,2007,90:072902.
[190] Lee Y H, Wu J M, Chueh Y L, et al. Low-temperature growth and interfacecharacterization of BiFeO3thin films with reduced leakage current. Appl Phys Lett,2005,87:172901.
[191]徐家跃,金敏.新型弛豫铁电晶体——生长、性能及应用.北京：化学工业出版社,2008.
[192]戴振国,董胜明,尹振华,等. PMN-PT晶体的生长、性质和应用进展.人工晶体学报,2005,34:1018-1023.
[193] Thiele C, Dorr K, Fahler S, et al. Voltage-controlled epitaxial strain inLa0.7Sr0.3MnO3/Pb(Mg1/3Nb2/3)O3-PbTiO3(001) films. Appl Phys Lett,2005,87:262502.
[194] Doerr K, Bilani-Zeneli O, Herklotz A, et al. A model system for strain effects:epitaxial magnetic films on a piezoelectric substrate. Eur Phys J B,2009,71:361-366.
[195] Doerr K, Thiele C, Bilani O, et al. Dynamic strain in magnetic films on piezoelectriccrystals. J Magn Magn Mater,2007,310:1182-1184.
[196] Chen Q P, Yang J J, Zhao Y G, et al. Electric-field control of phase separation andmemory effect in Pr0.6Ca0.4MnO3/Pb(Mg1/3Nb2/3)0.7Ti0.3O3heterostructures. Appl PhysLett,2011,98:172507.
[197] Zheng R K, Jiang Y, Wang Y, et al. Ferroelectric poling andconverse-piezoelectric-effect-induced strain effects in La0.7Ba0.3MnO3thin filmsgrown on ferroelectric single-crystal substrates. Phys Rev B,2009,79:174420.
[198] Huhne R, Okai D, Dorr K, et al. Dynamic investigations on the influence of epitaxialstrain on the superconducting transition in YBa2Cu3O7-x. Supercond Sci Technol,2008,21:075020.
[199] Liu M, Obi O, Lou J, et al. Giant electric field tuning of magnetic properties inmultiferroic ferrite/ferroelectric heterostructures. Adv Funct Mater,2009,19:1826-1831.
[200] Yang J J, Zhao Y G, Tian H F, et al. Electric field manipulation of magnetization atroom temperature in multiferroic CoFe2O4/Pb(Mg1/3Nb2/3)0.7Ti0.3O3heterostructures.Appl Phys Lett,2009,94:212504.
[201] Park J H, Jeong Y K, Ryu S, et al. Electric-field-control of magnetic remanence ofNiFe2O4thin film epitaxially grown on Pb(Mg1/3Nb2/3)O3-PbTiO3. Appl Phys Lett,2010,96:192504.
[202] Wu T, Bur A, Wong K, et al. Electrical control of reversible and permanentmagnetization reorientation for magnetoelectric memory devices. Appl Phys Lett,2011,98:262504.
[203] Zhang S, Zhao Y G, Li P S, et al. Electric-field control of nonvolatile magnetization inCo40Fe40B20/Pb(Mg1/3Nb2/3)0.7Ti0.3O3structure at room temperature. Phys Rev Lett,2012,108:137203.
[204]王慧.准同型相界附近PMN-PT的相结构研究[博士学位论文].北京：清华大学材料科学与工程系,2007.
[205] Wang H, Zhu J, Lu N, et al. Hierarchical micro-/nanoscale domain structure in MCphase of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3single crystal. Appl Phys Lett,2006,89:042908.
[206] Wang H, Zhu J, Zhang X W, et al. Domain structure of adaptive orthorhombic phase in110-poled Pb(Mg1/3Nb2/3)O3-30.5%PbTiO3single crystal. Appl Phys Lett,2008,92:132906.
[207] Wang H, Zhu J, Zhang X W, et al. Hierarchical domain structure of adaptive MBphasein Pb(Mg1/3Nb2/3)O3-32%PbTiO3single crystal. J Am Ceram Soc,2008,91:2382-2384.
[208] Li L. Ferroelectric/superconductor heterostructures. Mater Sci Eng R,2000,29:153-181.
[209] Ramesh R, Inam A, Chan W K, et al. Epitaxial cuprate superconductor ferroelectricheterostructures. Science,1991,252:944-946.
[210] Qi X Y, Yang H, Kong X, et al. Transmission electron microscopy ofBa0.7Sr0.3TiO3/YBa2Cu3O7-δepitaxial films on (001) SrTiO3substrates. J Cryst Growth,2004,262:353-358.
[211] Ahn C H, Gariglio S, Paruch P, et al. Electrostatic modulation of superconductivity inultrathin GdBa2Cu3O7-xfilms. Science,1999,284:1152-1155.
[212] Crassous A, Bernard R, Fusil S, et al. Nanoscale electrostatic manipulation ofmagnetic flux quanta in ferroelectric/superconductor BiFeO3/YBa2Cu3O7-δheterostructures. Phys Rev Lett,2011,107:247002.
[213]Lemanov V V, Kholkin A L, Sherman A B. YBCO thin films on ferroelectric substrates:The polarization-induced changes of superconductive properties. Supercond SciTechnol,1993,6:814-818.
[214] Wu X S, Jiang S S, Lam C C, et al. X-ray diffraction studies on YBa2Cu3O7-δwith Cosubstitution. Phys Status Solidi A,1996,157:439-447.
[215] Singh A K, Pandey D. Evidence for MBand MCphases in the morphotropic phaseboundary region of (1-x) Pb(Mg1/3Nb2/3)O3-xPbTiO3: A Rietveld study. Phys Rev B,2003,67:064102
[216] Zhai H Y, Rusakova I, Fairhurst R, et al. Different relaxation mechanisms of epitaxialstrain in YBa2Cu3O7-δfilms deposited on SrTiO3and LaAlO3. Philos Mag Lett,2001,81:683-690.
[217] Aindow M, Norris D J, Cheng T T. Misfit dislocations in laser-ablated heteroepitaxialYBa2Cu3O7-δon MgO(001). Philos Mag Lett,1996,74:267-272.
[218] Jia C L, Soltner H, Kabius B, et al. A study of antiphase boundaries and223planarfaults in epitaxial YBa2Cu3O7films by high-resolution electron microscopy. Physica C,1991,182:163-170.
[219] Lian J, Yao H B, Shi D L, et al. Structural characterization of epitaxial YBCO thinfilms prepared by a fluorine-free sol-gel method for coated conductors. Supercond SciTechnol,2003,16:838-844.
[220] Mori N, Teranishi R, Tada K, et al. Formation of microstructures and continuousheating and time-temperature transformation diagrams of YBa2Cu3O7-xfilm fabricatedby metal organic deposition with trifluoroacetates. Jpn J Appl Phys,2008,47:7131-7135.
[221] Mori N, Maebatake T, Teranishi R, et al. In situ observation and simulation of growthprocess of faceted RE123crystals. Physica C,2010,470:1266-1270.
[222] Karmanenko S F. Influence of growth rate on the structural orientation of YBCOsuperconducting films. Supercond Sci Technol,1999,12:36-44.
[223] Ziese M. Colossal magnetoresistance, half metallicity and spin electronics. Phil TransR Soc Lond A,2000,358:137-150.
[224] Asamitsu A, Tomioka Y, Kuwahara H, et al. Current switching of resistive states inmagnetoresistive manganites. Nature,1997,388:50-52.
[225] Yunoki S, Hu J, Malvezzi A L, et al. Phase separation in electronic models formanganites. Phys Rev Lett,1998,80:845-848.
[226] Uehara M, Mori S, Chen C H, et al. Percolative phase separation underlies colossalmagnetoresistance in mixed-valent manganites. Nature,1999,399:560-563.
[227] Mayr M, Moreo A, Verges J A, et al. Resistivity of mixed-phase manganites. Phys RevLett,2001,86:135-138.
[228] Fath M, Freisem S, Menovsky A A, et al. Spatially inhomogeneous metal-insulatortransition in doped manganites. Science,1999,285:1540-1542.
[229] Renner C, Aeppli G, Kim B G, et al. Atomic-scale images of charge ordering in amixed-valence manganite. Nature,2002,416:518-521.
[230] Zhang L W, Israel C, Biswas A, et al. Direct observation of percolation in a manganitethin film. Science,2002,298:805-807.
[231] Van Tendeloo G, Lebedev O I, Amelinckx S. Atomic and microstructure of CMRmaterials. J Magn Magn Mater,2000,211:73-83.
[232] Li D X, Wang M G, Ye H Q. Characterization of the microstructure in CMR materialsby HREM. J Electron Microsc,2002,51: S271-S278.
[233] Lebedev O I, Van Tendeloo G, Amelinckx S. Misfit accommodation of epitaxialLa1-xAXMnO3(A=Ca, Sr) thin films. Int J Inorg Mater,2001,3:1331-1337.
[234] Lebedev O I, Van Tendeloo G, Amelinckx S, et al. Periodic microtwinning as apossible mechanism for the accommodation of the epitaxial film-substrate mismatchin the La1-xSrxMnO3/SrTiO3system. Philos Mag A,2001,81:797-824.
[235] Lebedev O I, Verbeeck J, Van Tendeloo G, et al. Structure and microstructure ofLa1-xSrxMnO3(x approximate to0.16) films grown on a SrTiO3(110) substrate. PhilosMag A,2001,81:2865-2884.
[236] Fujimoto M, Koyama H, Nishi Y, et al. Crystallographic domain structure of anepitaxial Pr0.7Ca0.3MnO3thin film grown on a SrTiO single crystal substrate. J AmCeram Soc,2007,90:2205-2209.
[237] Zhu Y L, Wang X, Zhuo M J, et al. Dislocations in charge-ordered Pr0.5Ca0.5MnO3epitaxial thin films prepared by a two-step growth technique. Philos Mag Lett,2010,90:323-336.
[238]陈前平.电场对磁性/铁电多铁异质结构磁性调控的研究[博士学位论文].北京：清华大学物理系,2012.
[239] Fukumoto N, Mori S, Yamamoto N, et al. Microscopic electronic phase separation andmetal-insulator transition in Nd0.5Sr0.5MnO3. Phys Rev B,1999,60:12963-12967.
[2] Fiebig M. Revival of the magnetoelectric effect. J Phys D Appl Phys,2005,38:R123-R152.
[3] Eerenstein W, Mathur N D, Scott J F. Multiferroic and magnetoelectric materials.Nature,2006,442:759-765.
[4] Ramesh R, Spaldin N A. Multiferroics: progress and prospects in thin films. NatureMater,2007,6:21-29.
[5] Cheong S W, Mostovoy M. Multiferroics: a magnetic twist for ferroelectricity. NatureMater,2007,6:13-20.
[6] Tokura Y. Multiferroics-toward strong coupling between magnetization andpolarization in a solid. J Magn Magn Mater,2007,310:1145-1150.
[7] Prellier W, Singh M P, Murugavel P. The single-phase multiferroic oxides: from bulkto thin film. J Phys: Condens Matter,2005,17: R803-R832.
[8] Khomskii D I. Multiferroics: Different ways to combine magnetism andferroelectricity. J Magn Magn Mater,2006,306:1-8.
[9] Spaldin N A, Fiebig M. The renaissance of magnetoelectric multiferroics. Science,2005,309:391-392.
[10]王克锋,刘俊明,王雨.单相多铁性材料——极化和磁性序参量的耦合与调控.科学通报,2008,53:1098-1135.
[11]迟振华,靳常青.单相磁电多铁性体研究进展.物理学进展,2007,27:225-238.
[12]何泓材,林元华,南策文.多铁性磁电复合薄膜.科学通报,2008,53:1136-1148.
[13] Curie P. Sur la symétrie dans les phénomenes physiques, symétrie d'un champ électrique et d'un champ magnétique. J Phys,1894,3(Ser. Ⅲ):393-415.
[14] Astrov D N. The magnetoelectric effect in antiferromagnetics. Soviet PhysicsJetp-Ussr,1960,11:708-709.
[15] Tokura Y. Materials science-Multiferroics as quantum electromagnets. Science,2006,312:1481-1482.
[16] Hill N A. Why are there so few magnetic ferroelectrics? J Phys Chem B,2000,104:6694-6709.
[17] Nan C W, Bichurin M I, Dong S X, et al. Multiferroic magnetoelectric composites:Historical perspective, status, and future directions. J Appl Phys,2008,103:031101.
[18] Wang Y, Hu J M, Lin Y H, et al. Multiferroic magnetoelectric compositenanostructures. Npg Asia Materials,2010,2:61-68.
[19] Ma J, Hu J M, Li Z, et al. Recent progress in multiferroic magnetoelectric composites:from bulk to thin films. Adv Mater,2011,23:1062-1087.
[20] Vaz C A F, Hoffman J, Anh C H, et al. Magnetoelectric coupling effects in multiferroiccomplex oxide composite structures. Adv Mater,2010,22:2900-2918.
[21] Atou T, Chiba H, Ohoyama K, et al. Structure determination of ferromagneticperovskite BiMnO3. J Solid State Chem,1999,145:639-642.
[22] Kimura T, Kawamoto S, Yamada I, et al. Magnetocapacitance effect in multiferroicBiMnO3. Phys Rev B,2003,67:180401.
[23] Martin L, Crane S P, Chu Y H, et al. Multiferroics and magnetoelectrics: thin filmsand nanostructures. J Phys: Condens Matter,2008,20:434220.
[24] Graboy I E, Bosak A A, Gorbenko O Y, et al. HREM study of epitaxially stabilizedhexagonal rare earth manganites. Chem Mater,2003,15:2632-2637.
[25] Van Aken B B, Palstra T T M, Filippetti A, et al. The origin of ferroelectricity inmagnetoelectric YMnO3. Nature Mater,2004,3:164-170.
[26] Wang K F, Liu J M, Ren Z F. Multiferroicity: the coupling between magnetic andpolarization orders. Adv Phys,2009,58:321-448.
[27] Lottermoser T, Lonkai T, Amann U, et al. Magnetic phase control by an electric field.Nature,2004,430:541-544.
[28] Rogez G, Viart N, Drillon M. Multiferroic materials: The attractive approach ofmetal-organic frameworks (MOFs). Angew Chem Int Ed,2010,49:1921-1923.
[29] Fabreges X, Petit S, Mirebeau I, et al. Spin-lattice coupling, frustration, and magneticorder in multiferroic RMnO3. Phys Rev Lett,2009,103:067204.
[30] Ren C Y. Atomic, electronic, and ferroelectric properties of manganite RMnO3(R=Ho,Er,Tm,Lu) in hexagonal and orthorhombic phases. Phys Rev B,2009,79:125113.
[31] Kimura T, Goto T, Shintani H, et al. Magnetic control of ferroelectric polarization.Nature,2003,426:55-58.
[32] Yamasaki Y, Sagayama H, Goto T, et al. Electric control of spin helicity in a magneticferroelectric. Phys Rev Lett,2007,98:147204.
[33] Yamasaki Y, Miyasaka S, Kaneko Y, et al. Magnetic reversal of the ferroelectricpolarization in a multiferroic spinel oxide. Phys Rev Lett,2006,96:207204.
[34] Portengen T, Ostreich T, Sham L J. Theory of electronic ferroelectricity. Phys Rev B,1996,54:17452-17463.
[35] Ikeda N, Ohsumi H, Ohwada K, et al. Ferroelectricity from iron valence ordering inthe charge-frustrated system LuFe2O4. Nature,2005,436:1136-1138.
[36] Dagotto E, Hotta T, Moreo A. Colossal magnetoresistant materials: The key role ofphase separation. Phys Rep,2001,344:1-153.
[37] Efremov D V, Van den Brink J, Khomskii D I. Bond-versus site-centred ordering andpossible ferroelectricity in manganites. Nature Mater,2004,3:853-856.
[38] van den Brink J, Khomskii D I. Multiferroicity due to charge ordering. J Phys:Condens Matter,2008,20:434217.
[39] Jooss C, Wu L, Beetz T, et al. Polaron melting and ordering as key mechanisms forcolossal resistance effects in manganites. Proc Natl Acad Sci,2007,104:13597-13602.
[40] Zheng H, Wang J, Lofland S E, et al. Multiferroic BaTiO3-CoFe2O4nanostructures.Science,2004,303:661-663.
[41] Zheng H M, Straub F, Zhan Q, et al. Self-assembled growth of BiFeO3-CoFe2O4nanostructures. Adv Mater,2006,18:2747-2752.
[42] Zheng H, Zhan Q, Zavaliche F, et al. Controlling self-assembled perovskite-spinelnanostructures. Nano Lett,2006,6:1401-1407.
[43] Molegraaf H J A, Hoffman J, Vaz C A F, et al. Magnetoelectric effects in complexoxides with competing ground states. Adv Mater,2009,21:3470-3474.
[44] Thiele C, Doerr K, Bilani O, et al. Influence of strain on the magnetization andmagnetoelectric effect in La0.7A0.3MnO3/PMN-PT(001)(A=Sr,Ca). Phys Rev B,2007,75:054408.
[45]章晓中.电子显微分析.北京：清华大学出版社,2006.
[46]朱静,叶恒强,王仁卉,等.高空间分辨分析电子显微学.北京：科学出版社,1985.
[47]叶恒强,王元明.透射电子显微学进展.北京：科学出版社,2003.
[48] Williams D B, Carter C B. Transmission electron microscopy: A text book formaterials science. New York: Plenum,1996.
[49] Zhan Q, Yu R, Crane S P, et al. Structure and interface chemistry of perovskite-spinelnanocomposite thin films. Appl Phys Lett,2006,89:172902.
[50] Zeches R J, Rossell M D, Zhang J X, et al. A strain-driven morphotropic phaseboundary in BiFeO3. Science,2009,326:977-980.
[51] Borisevich A Y, Chang H J, Huijben M, et al. Suppression of Octahedral Tilts andAssociated Changes in Electronic Properties at Epitaxial Oxide HeterostructureInterfaces. Phys Rev Lett,2010,105:087204.
[52] Zhang J X, He Q, Trassin M, et al. Microscopic origin of the giant ferroelectricpolarization in tetragonal-like BiFeO3. Phys Rev Lett,2011,107:147602.
[53] Zhang J X, Xiang B, He Q, et al. Large field-induced strains in a lead-freepiezoelectric material. Nature Nanotechnol,2011,6:97-101.
[54] Rossell M D, Erni R, Prange M P, et al. Atomic structure of highly strained BiFeO3thin films. Phys Rev Lett,2012,108:047601.
[55] Lubk A, Rossell M D, Seidel J, et al. Evidence of sharp and diffuse domain walls inBiFeO3by means of unit-cell-wise strain and polarization maps obtained with highresolution scanning transmission electron microscopy. Phys Rev Lett,2012,109:047601.
[56] Chen Y B, Katz M B, Pan X Q, et al. Ferroelectric domain structures of epitaxial (001)BiFeO3thin films. Appl Phys Lett,2007,90:072907.
[57] Nelson C T, Winchester B, Zhang Y, et al. Spontaneous vortex nanodomain arrays atferroelectric heterointerfaces. Nano Lett,2011,11:828-834.
[58] Nelson C T, Gao P, Jokisaari J R, et al. Domain dynamics during ferroelectricswitching. Science,2011,334:968-971.
[59] Gao P, Nelson C T, Jokisaari J R, et al. Revealing the role of defects in ferroelectricswitching with atomic resolution. Nature Commun,2011,2:591.
[60] Gao P, Nelson C T, Jokisaari J R, et al. Direct observations of retention failure inferroelectric memories. Adv Mater,2012,24:1106-1110.
[61] Cheng C J, Borisevich A Y, Kan D, et al. Nanoscale structural and chemical propertiesof antipolar clusters in Sm-doped BiFeO3ferroelectric epitaxial thin films. ChemMater,2010,22:2588-2596.
[62] Borisevich A Y, Eliseev E A, Morozovska A N, et al. Atomic-scale evolution ofmodulated phases at the ferroelectric-antiferroelectric morphotropic phase boundarycontrolled by flexoelectric interaction. Nature Commun.,2012,3:775.
[63] Yang H, Chi Z H, Yao L D, et al. Structural defects in multiferroic BiMnO3studied bytransmission electron microscopy and electron energy-loss spectroscopy. J Appl Phys,2006,100:044105.
[64] Bosak A A, Kamenev A A, Graboy I E, et al. Epitaxial phase stabilisation phenomenain rare earth manganites. Thin Solid Films,2001,400:149-153.
[65] Salvador P A, Doan T D, Mercey B, et al. Stabilization of YMnO3in a perovskitestructure as a thin film. Chem Mater,1998,10:2592-2595.
[66] Lee J H, Murugavel P, Ryu H, et al. Epitaxial stabilization of a new multiferroichexagonal phase of TbMnO3thin films. Adv Mater,2006,18:3125-3129.
[67] Jehanathan N, Lebedev O, Gelard I, et al. Structure and defect characterization ofmultiferroic ReMnO3films and multilayers by TEM. Nanotechnology,2010,21:075705.
[68] Han T C, Lin J G. Substrate dependent structure and magnetic properties in HoMnO3films. IEEE Trans Magn,2008,44:2930-2932.
[69] Lin J G, Han T C, Wu C T, et al. Directional growth and characterizations oforthorhombic HoMnO3films. J Cryst Growth,2008,310:3878-3880.
[70] Han T C, Lin J G. Strong coupling of magnetic and dielectric properties in the a-axisoriented orthorhombic HoMnO3films. Appl Phys Lett,2009,94:082502.
[71] Han T C, Chao H H. Observation of large electric polarization in orthorhombicTmMnO3thin films. Appl Phys Lett,2010,97:232902.
[72] Zhang Y, Yang H X, Ma C, et al. Charge-stripe order in the electronic ferroelectricLuFe2O4. Phys Rev Lett,2007,98:247602.
[73] Schattschneider P, Rubino S, Hebert C, et al. Detection of magnetic circular dichroismusing a transmission electron microscope. Nature,2006,441:486-488.
[74] Schattschneider P, Hebert C, Rubino S, et al. Magnetic circular dichroism in EELS:Towards10nm resolution. Ultramicroscopy,2008,108:433-438.
[75] Rubino S, Schattschneider P, Stoger-Pollach M, et al. Energy-loss magnetic chiraldichroism (EMCD): Magnetic chiral dichroism in the electron microscope. J MaterRes,2008,23:2582-2590.
[76] Schattschneider P, Rubino S, Stoeger-Pollach M, et al. Energy loss magnetic chiraldichroism: A new technique for the study of magnetic properties in the electronmicroscope (invited). J Appl Phys,2008,103:07D931.
[77] Lidbaum H, Rusz J, Liebig A, et al. Quantitative magnetic information from reciprocalspace maps in transmission electron microscopy. Phys Rev Lett,2009,102.
[78] Zhang Z H, Wang X F, Xu J B, et al. Evidence of intrinsic ferromagnetism inindividual dilute magnetic semiconducting nanostructures. Nature Nanotechnol,2009,4:523-527.
[79] Wang Z Q, Zhong X Y, Yu R, et al. Quantitative experimental determination ofsite-specific magnetic structures by transmitted electrons. Nature Commun,2013,4:1395.
[80] Uchida M, Onose Y, Matsui Y, et al. Real-space observation of helical spin order.Science,2006,311:359-361.
[81] Zhao T, Scholl A, Zavaliche F, et al. Electrical control of antiferromagnetic domainsin multiferroic BiFeO3films at room temperature. Nature Mater,2006,5:823-829.
[82] Zavaliche F, Yang S Y, Zhao T, et al. Multiferroic BiFeO3films: domain structure andpolarization dynamics. Phase Transit,2006,79:991-1017.
[83] Chu Y H, Martin L W, Holcomb M B, et al. Electric-field control of localferromagnetism using a magnetoelectric multiferroic. Nature Mater,2008,7:478-482.
[84] Seidel J, Martin L W, He Q, et al. Conduction at domain walls in oxide multiferroics.Nature Mater,2009,8:229-234.
[85] Heron J T, Trassin M, Ashraf K, et al. Electric-field-induced magnetization reversal ina ferromagnet-multiferroic heterostructure. Phys Rev Lett,2011,107:217202.
[86] Maksymovych P, Seidel J, Chu Y H, et al. Dynamic conductivity of ferroelectricdomain walls in BiFeO3. Nano Lett,2011,11:1906-1912.
[87] Zavaliche F, Zhao T, Zheng H, et al. Electrically assisted magnetic recording inmultiferroic nanostructures. Nano Lett,2007,7:1586-1590.
[88] Fiebig M, Frohlich D, Lottermoser T, et al. Probing of ferroelectric surface and bulkdomains in RMnO3(R=Y, Ho) by second harmonic generation. Phys Rev B,2002,66:144102.
[89] Lottermoser T, Fiebig M. Magnetoelectric behavior of domain walls in multiferroicHoMnO3. Phys Rev B,2004,70:220407.
[90] Van Aken B B, Rivera J P, Schmid H, et al. Observation of ferrotoroidic domains.Nature,2007,449:702-705.
[91]进藤大辅,平贺贤二.材料评价的高分辨电子显微方法.北京：冶金工业出版社,1998.
[92]王蓉.电子衍射物理教程.北京：冶金工业出版社,2002.
[93] Cowley J M. Diffraction physics.3rd ed. Amsterdam: Elsevier,1995.
[94]李方华.电子晶体学与图像处理.上海：上海科学技术出版社,2009.
[95] Spence J C H. High-resolution electron microscopy.3rd ed. New York: Oxford,2003.
[96] O'Keefe M A, Kilaas R. Adcances in high-resolution image simulation. Scan MicroscSuppl,1988,2:225-244.
[97] Haider M, Uhlemann S, Schwan E, et al. Electron microscopy image enhanced. Nature,1998,392:768-769.
[98] Haider M, Rose H, Uhlemann S, et al. A spherical-aberration-corrected200kVtransmission electron microscope. Ultramicroscopy,1998,75:53-60.
[99] Rose H. Elektronenoptische aplanate. Optik,1971,34:285-311.
[100] Urban K W. Studying atomic structures by aberration-corrected transmission electronmicroscopy. Science,2008,321:506-510.
[101] Jia C L, Lentzen M, Urban K. Atomic-resolution imaging of oxygen in perovskiteceramics. Science,2003,299:870-873.
[102] Houben L, Thust A, Urban K. Atomic-precision determination of the reconstruction ofa90degrees tilt boundary in YBa2Cu3O7-δby aberration corrected HRTEM.Ultramicroscopy,2006,106:200-214.
[103] Jia C L, Mi S B, Urban K, et al. Atomic-scale study of electric dipoles near chargedand uncharged domain walls in ferroelectric films. Nature Mater,2008,7:57-61.
[104] Jia C L, Mi S B, Urban K, et al. Effect of a single dislocation in a heterostructure layeron the local polarization of a ferroelectric layer. Phys Rev Lett,2009,102:117601.
[105] Urban K W. Is science prepared for atomic-resolution electron microscopy? NatureMater,2009,8:260-262.
[106] Jia C L, Urban K W, Alexe M, et al. Direct observation of continuous electric dipolerotation in flux-closure domains in ferroelectric Pb(Zr,Ti)O3. Science,2011,331:1420-1423.
[107] Uhlemann S, Haider M. Residual wave aberrations in the first spherical aberrationcorrected transmission electron microscope. Ultramicroscopy,1998,72:109-119.
[108] Schramm S M, van der Molen S J, Tromp R M. Intrinsic instability ofaberration-corrected electron microscopes. Phys Rev Lett,2012,109:163901.
[109] Muller D A. Structure and bonding at the atomic scale by scanning transmissionelectron microscopy. Nature Mater,2009,8:263-270.
[110] Krivanek O L, Chisholm M F, Nicolosi V, et al. Atom-by-atom structural and chemicalanalysis by annular dark-field electron microscopy. Nature,2010,464:571-574.
[111] Ishikawa R, Okunishi E, Sawada H, et al. Direct imaging of hydrogen atom columns ina crystal by annular bright-field electron microscopy. Nature Mater,2011,10:278-281.
[112] Huang R, Hitosugi T, Findlay S D, et al. Real-time direct observation of Li in LiCoO2cathode material. Appl Phys Lett,2011,98:051913.
[113] Gu L, Zhu C B, Li H, et al. Direct observation of Lithium staging in partiallydelithiated LiFePO4at atomic resolution. J Am Chem Soc,2011,133:4661-4663.
[114] Lu X, Zhao L, He X Q, et al. Lithium storage in Li4Ti5O12spinel: The full staticpicture from electron microscopy. Adv Mater,2012,24:3233-3238.
[115] Egerton R F. Electron energy-loss spectroscopy in the electron microscope.2nd ed.New York: Plenum,1996.
[116]进藤大辅,及川哲夫.材料评价的分析电子显微方法.北京：冶金工业出版社,2001.
[117] Egerton R F. Electron energy-loss spectroscopy in the TEM. Rep Prog Phys,2009,72:016502.
[118] Pearson D H, Ahn C C, Fultz B. White lines and d-electron occupancies for the3d and4d transition metals. Phys Rev B,1993,47:8471-8478.
[119] Cho D Y, Kim J Y, Park B G, et al. Ferroelectricity driven by Y d0-ness withrehybridization in YMnO3. Phys Rev Lett,2007,98:217601.
[120] Zhong C G, Jiang Q, Zhang H, et al. Effect of spin frustration and spin-orbit couplingon the ferroelectric polarization in multiferroic YMnO3. Appl Phys Lett,2009,94:224107.
[121] Kim J, Cho K C, Koo Y M, et al. Y-O hybridization in the ferroelectric transition ofYMnO3. Appl Phys Lett,2009,95:132901.
[122] Oak M A, Lee J H, Jang H M, et al.4d-5p Orbital mixing and asymmetric In4d-O2phybridization in InMnO3: A new bonding mechanism for hexagonal ferroelectricity.Phys Rev Lett,2011,106:047601.
[123] Lee S, Pirogov A, Kang M S, et al. Giant magneto-elastic coupling in multiferroichexagonal manganites. Nature,2008,451:805-808.
[124] Choi T, Horibe Y, Yi H T, et al. Insulating interlocked ferroelectric and structuralantiphase domain walls in multiferroic YMnO3. Nature Mater,2010,9:253-258.
[125] Mostovoy M. Multiferroics: A whirlwind of opportunities. Nature Mater,2010,9:188-190.
[126] Chae S C, Horibe Y, Jeong D Y, et al. Self-organization, condensation, andannihilation of topological vortices and antivortices in a multiferroic. Proc Natl AcadSci,2010,107:21366-21370.
[127] Jungk T, Hoffmann A, Fiebig M, et al. Electrostatic topology of ferroelectric domainsin YMnO3. Appl Phys Lett,2010,97:012904.
[128] Chae S C, Lee N, Horibe Y, et al. Direct observation of the proliferation offerroelectric loop domains and vortex-antivortex pairs. Phys Rev Lett,2012,108:167603.
[129] Geng Y N, Lee N, Choi Y J, et al. Collective magnetism at multiferroic vortex domainwalls. Nano Lett,2012,12:6055-6059.
[130] Wu W D, Guest J R, Horibe Y, et al. Polarization-modulated rectification atferroelectric surfaces. Phys Rev Lett,2010,104:217601.
[131] Wu W D, Horibe Y, Lee N, et al. Conduction of topologically protected chargedferroelectric domain walls. Phys Rev Lett,2012,108:077203.
[132] Meier D, Seidel J, Cano A, et al. Anisotropic conductance at improper ferroelectricdomain walls. Nature Mater,2012,11:284-288.
[133] Safrankova M, Fousek J, Kizaev S A. Domains in ferroelectric YMnO3. Czech J PhysSect B1967,17:559-560.
[134] Chaikin P M, Lubensky T C. Principles of condensed matter physics. Cambridge:Cambridge Univ,1995.
[135] Wang X M, Fan C, Zhao Z Y, et al. Large magnetothermal conductivity of HoMnO3single crystals and its relation to the magnetic-field-induced transitions of magneticstructure. Phys Rev B,2010,82:094405.
[136] Catlow C R A. Solid state chemistry: Techniques. ed. by Cheetham A K, Day P.Oxford: Clarendon,1987.
[137] Catlow C R A. Computer modelling in inorganic crystallography. San Diego:Academic,1997.
[138] Zhang C, Zhang X, Sun Y, et al. Atomistic simulation of Y-site substitution inmultiferroic h-YMnO3. Phys Rev B,2011,83:054104.
[139] Jiang N, Zhang X. Atomistic simulation of Mn-site substitution in multiferroich-YMnO3. J Phys: Condens Matter,2012,24:235402.
[140] Dick B G, Overhauser A W. Theory of the dielectric constants of alkali halide crystals.Phys Rev,1958,112:90-103.
[141] Mott M F, Littleton M J. Conduction in polar crystals. I. Electrolytic conduction insolid salts. Trans Faraday Soc,1938,34:0485-0499.
[142] Gale J D, Rohl A L. The general utility lattice program (GULP). Mol Simulat,2003,29:291-341.
[143] Katsufuji T, Mori S, Masaki M, et al. Dielectric and magnetic anomalies and spinfrustration in hexagonal RMnO3(R=Y, Yb, and Lu). Phys Rev B,2001,64:104419.
[144] Li J, Yang H X, Tian H F, et al. Scanning secondary-electron microscopy onferroelectric domains and domain walls in YMnO3. Appl Phys Lett,2012,100:152903.
[145] Kumagai Y, Spaldin N A. Structural domain walls in polar hexagonal manganites.Nature Commun,2013,4:1540.
[146] Artyukhin S, Delaney K T, Spaldin N A, et al. Landau theory of topological defects inmultiferroic hexagonal manganites.(2012) http://arxiv.org/abs/1204.4126.
[147] Chang H J, Kalinin S V, Morozovska A N, et al. Atomically resolved mapping ofpolarization and electric fields across ferroelectric/oxide interfaces by Z-contrastimaging. Adv Mater,2011,23:2474-2479.
[148] Fong D D, Cionca C, Yacoby Y, et al. Direct structural determination in ultrathinferroelectric films by analysis of synchrotron x-ray scattering measurements. PhysRev B,2005,71:144112.
[149] Zhang Q H, Wang L J, Wei X K, et al. Direct observation of interlocked domain wallsin hexagonal RMnO3(R=Tm, Lu). Phys Rev B,2012,85:020102.
[150] Fujimura N, Ishida T, Yoshimura T, et al. Epitaxially grown YMnO3film: Newcandidate for nonvolatile memory devices. Appl Phys Lett,1996,69:1011-1013.
[151] Murugavel P, Lee J H, Lee D, et al. Physical properties of multiferroic hexagonalHoMnO3thin films. Appl Phys Lett,2007,90:142902.
[152] Lee D, Yoon A, Jang S Y, et al. Giant flexoelectric effect in ferroelectric epitaxial thinfilms. Phys Rev Lett,2011,107:057602.
[153] Laukhin V, Skumryev V, Marti X, et al. Electric-field control of exchange bias inmultiferroic epitaxial heterostructures. Phys Rev Lett,2006,97:227201.
[154] Munoz A, Alonso J A, Martinez-Lope M J, et al. Evolution of the magnetic structureof hexagonal HoMnO3from neutron powder diffraction data. Chem Mater,2001,13:1497-1505.
[155] Horiuchi H, Schultz A J, Leung P C W, et al. Time-of-flight neutron diffraction studyof a single crystal of yttria-stabilized zirconia, Zr(Y)O1.862, at high temperature and inan applied electrical field. Acta Crystallogr B,1984,40:367-372.
[156] Zurbuchen M A, Tian W, Pan X Q, et al. Morphology, structure, and nucleation ofout-of-phase boundaries (OPBs) in epitaxial films of layered oxides. J Mater Res,2007,22:1439-1471.
[157] Gelard I, Jehanathan N, Roussel H, et al. Off-Stoichiometry effects on the crystallineand defect structure of hexagonal manganite REMnO3films (RE=V, Er, Dy). ChemMater,2011,23:1232-1238.
[158] Saterli R. Electronic structure of thermoelectric and ferroelectric materials-advancedtransmission electron microscopy studies[Dotoral thesis]. Norway: Department ofPhysics, Norwegian University of Science and Technology,2010.
[159] Pomjakushin V Y, Kenzelmann M, Donni A, et al. Evidence for large electricpolarization from collinear magnetism in TmMnO3. New Journal of Physics,2009,11:043019.
[160] Feng S M, Chai Y S, Zhu J L, et al. Determination of the intrinsic ferroelectricpolarization in orthorhombic HoMnO3. New Journal of Physics,2010,12:073006.
[161] Brinks H W, Rodriguez-Carvajal J, Fjellvag H, et al. Crystal and magnetic structure oforthorhombic HoMnO3. Phys Rev B,2001,63:094411.
[162] Munoz A, Alonso J A, Casais M T, et al. The magnetic structure of YMnO3perovskiterevisited. J Phys: Condens Matter,2002,14:3285-3294.
[163] Nakamura M, Tokunaga Y, Kawasaki M, et al. Multiferroicity in an orthorhombicYMnO3single-crystal film. Appl Phys Lett,2011,98:082902.
[164] Fontcuberta J, Fina I, Fabrega L, et al. Ferroelectricity and strain effects inorthorhombic YMnO3thin films. Phase Transit,2011,84:555-568.
[165] Marti X, Skumryev V, Laukhin V, et al. Strain-driven noncollinear magnetic orderingin orthorhombic epitaxial YMnO3thin films. J Appl Phys,2010,108:123917.
[166] Marti X, Skumryev V, Ferrater C, et al. Emergence of ferromagnetism inantiferromagnetic TbMnO3by epitaxial strain. Appl Phys Lett,2010,96:222505.
[167] Lin T H, Shih H C, Hsieh C C, et al. Strain-induced effects on antiferromagneticordering and magnetocapacitance in orthorhombic HoMnO3thin films. J Phys:Condens Matter,2009,21:026013.
[168] Marti X, Fina I, Skumryev V, et al. Strain tuned magnetoelectric coupling inorthorhombic YMnO3thin films. Appl Phys Lett,2009,95:142903.
[169]杨军杰.多铁异质结构电、磁特性的调控[博士学位论文].北京：清华大学物理系,2010.
[170] Matthews J W, Blakeslee A E. Defects in epitaxial multilayers.1. Misfit dislocations.J Cryst Growth,1974,27:118-125.
[171] Martin L W, Chu Y H, Ramesh R. Advances in the growth and characterization ofmagnetic, ferroelectric, and multiferroic oxide thin films. Mater Sci Eng R,2010,68:89-133.
[172] Qin Y L, Jia C L, Urban K, et al. Dislocations in SrTiO3thin films grown on LaAlO3substrates. J Mater Res,2002,17:3117-3126.
[173] Suzuki T, Nishi Y, Fujimoto M. Analysis of misfit relaxation in heteroepitaxial BaTiO3thin films. Philos Mag A,1999,79:2461-2483.
[174] Chen Y B, Katz M B, Pan X Q, et al. Microstructure and strain relaxation of epitaxialPrScO3thin films grown on (001) SrTiO3substrates. Appl Phys Lett,2007,91:031902.
[175] Gorbenko O Y, Samoilenkov S V, Graboy I E, et al. Epitaxial stabilization of oxides inthin films. Chem Mater,2002,14:4026-4043.
[176] Li Y, Weatherly G C, Niewczas M. TEM studies of stress relaxation in GaAsN andGaP thin films. Philos Mag,2005,85:3073-3090.
[177] Jonsdottir F. Computation of equilibrium surface fluctuations in strained epitaxialfilms due to interface misfit dislocations. Model Simul Mater Sc,1995,3:503-520.
[178] Wang J, Neaton J B, Zheng H, et al. Epitaxial BiFeO3multiferroic thin filmheterostructures. Science,2003,299:1719-1722.
[179] Choi T, Lee S, Choi Y J, et al. Switchable ferroelectric diode and photovoltaic effectin BiFeO3. Science,2009,324:63-66.
[180] Kim J K, Kim S S, Kim W J, et al. Enhanced ferroelectric properties of Cr-dopedBiFeO3thin films grown by chemical solution deposition. Appl Phys Lett,2006,88:132901.
[181] Wang Y, Nan C W. Enhanced ferroelectricity in Ti-doped multiferroic BiFeO3thinfilms. Appl Phys Lett,2006,89:052903.
[182] Palkar V R, Kumara K G, Malik S K. Observation of room-temperaturemagnetoelectric coupling in pulsed-laser-deposited Bi0.6Tb0.3La0.1FeO3thin films.Appl Phys Lett,2004,84:2856-2858.
[183] Chung C F, Lin J P, Wu J M. Influence of Mn and Nb dopants on electric properties ofchemical-solution-deposited BiFeO3films. Appl Phys Lett,2006,88:242909.
[184] Kim J K, Kim S S, Park M H, et al. Microstructure and electrical properties ofcosubstituted BiFeO3thin films prepared by a chemical solution deposition.Ferroelectrics,2006,345:77-82.
[185] Cui Y F, Zhao Y G, Luo L B, et al. Dielectric, magnetic, and magnetoelectricproperties of La and Ti codoped BiFeO3. Appl Phys Lett,2010,97:222904.
[186] Wu J G, Wang J. Ferroelectric and impedance behavior of La-and Ti-Codoped BiFeO3thin films. J Am Ceram Soc,2010,93:2795-2803.
[187] Brydson R, Sauer H, Engel W, et al. Electron-energy loss and X-ray absorptionspectroscopy of rutile and anatase: A test of structural sensitivity. J Phys: CondensMatter,1989,1:797-812.
[188] Sparrow T G, Williams B G, Rao C N R, et al. L3/L2white-line intensity ratios in theelectron energy-loss spectra of3d transition-metal oxides. Chem Phys Lett,1984,108:547-550.
[189] Pabst G W, Martin L W, Chu Y H, et al. Leakage mechanisms in BiFeO3thin films.Appl Phys Lett,2007,90:072902.
[190] Lee Y H, Wu J M, Chueh Y L, et al. Low-temperature growth and interfacecharacterization of BiFeO3thin films with reduced leakage current. Appl Phys Lett,2005,87:172901.
[191]徐家跃,金敏.新型弛豫铁电晶体——生长、性能及应用.北京：化学工业出版社,2008.
[192]戴振国,董胜明,尹振华,等. PMN-PT晶体的生长、性质和应用进展.人工晶体学报,2005,34:1018-1023.
[193] Thiele C, Dorr K, Fahler S, et al. Voltage-controlled epitaxial strain inLa0.7Sr0.3MnO3/Pb(Mg1/3Nb2/3)O3-PbTiO3(001) films. Appl Phys Lett,2005,87:262502.
[194] Doerr K, Bilani-Zeneli O, Herklotz A, et al. A model system for strain effects:epitaxial magnetic films on a piezoelectric substrate. Eur Phys J B,2009,71:361-366.
[195] Doerr K, Thiele C, Bilani O, et al. Dynamic strain in magnetic films on piezoelectriccrystals. J Magn Magn Mater,2007,310:1182-1184.
[196] Chen Q P, Yang J J, Zhao Y G, et al. Electric-field control of phase separation andmemory effect in Pr0.6Ca0.4MnO3/Pb(Mg1/3Nb2/3)0.7Ti0.3O3heterostructures. Appl PhysLett,2011,98:172507.
[197] Zheng R K, Jiang Y, Wang Y, et al. Ferroelectric poling andconverse-piezoelectric-effect-induced strain effects in La0.7Ba0.3MnO3thin filmsgrown on ferroelectric single-crystal substrates. Phys Rev B,2009,79:174420.
[198] Huhne R, Okai D, Dorr K, et al. Dynamic investigations on the influence of epitaxialstrain on the superconducting transition in YBa2Cu3O7-x. Supercond Sci Technol,2008,21:075020.
[199] Liu M, Obi O, Lou J, et al. Giant electric field tuning of magnetic properties inmultiferroic ferrite/ferroelectric heterostructures. Adv Funct Mater,2009,19:1826-1831.
[200] Yang J J, Zhao Y G, Tian H F, et al. Electric field manipulation of magnetization atroom temperature in multiferroic CoFe2O4/Pb(Mg1/3Nb2/3)0.7Ti0.3O3heterostructures.Appl Phys Lett,2009,94:212504.
[201] Park J H, Jeong Y K, Ryu S, et al. Electric-field-control of magnetic remanence ofNiFe2O4thin film epitaxially grown on Pb(Mg1/3Nb2/3)O3-PbTiO3. Appl Phys Lett,2010,96:192504.
[202] Wu T, Bur A, Wong K, et al. Electrical control of reversible and permanentmagnetization reorientation for magnetoelectric memory devices. Appl Phys Lett,2011,98:262504.
[203] Zhang S, Zhao Y G, Li P S, et al. Electric-field control of nonvolatile magnetization inCo40Fe40B20/Pb(Mg1/3Nb2/3)0.7Ti0.3O3structure at room temperature. Phys Rev Lett,2012,108:137203.
[204]王慧.准同型相界附近PMN-PT的相结构研究[博士学位论文].北京：清华大学材料科学与工程系,2007.
[205] Wang H, Zhu J, Lu N, et al. Hierarchical micro-/nanoscale domain structure in MCphase of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3single crystal. Appl Phys Lett,2006,89:042908.
[206] Wang H, Zhu J, Zhang X W, et al. Domain structure of adaptive orthorhombic phase in110-poled Pb(Mg1/3Nb2/3)O3-30.5%PbTiO3single crystal. Appl Phys Lett,2008,92:132906.
[207] Wang H, Zhu J, Zhang X W, et al. Hierarchical domain structure of adaptive MBphasein Pb(Mg1/3Nb2/3)O3-32%PbTiO3single crystal. J Am Ceram Soc,2008,91:2382-2384.
[208] Li L. Ferroelectric/superconductor heterostructures. Mater Sci Eng R,2000,29:153-181.
[209] Ramesh R, Inam A, Chan W K, et al. Epitaxial cuprate superconductor ferroelectricheterostructures. Science,1991,252:944-946.
[210] Qi X Y, Yang H, Kong X, et al. Transmission electron microscopy ofBa0.7Sr0.3TiO3/YBa2Cu3O7-δepitaxial films on (001) SrTiO3substrates. J Cryst Growth,2004,262:353-358.
[211] Ahn C H, Gariglio S, Paruch P, et al. Electrostatic modulation of superconductivity inultrathin GdBa2Cu3O7-xfilms. Science,1999,284:1152-1155.
[212] Crassous A, Bernard R, Fusil S, et al. Nanoscale electrostatic manipulation ofmagnetic flux quanta in ferroelectric/superconductor BiFeO3/YBa2Cu3O7-δheterostructures. Phys Rev Lett,2011,107:247002.
[213]Lemanov V V, Kholkin A L, Sherman A B. YBCO thin films on ferroelectric substrates:The polarization-induced changes of superconductive properties. Supercond SciTechnol,1993,6:814-818.
[214] Wu X S, Jiang S S, Lam C C, et al. X-ray diffraction studies on YBa2Cu3O7-δwith Cosubstitution. Phys Status Solidi A,1996,157:439-447.
[215] Singh A K, Pandey D. Evidence for MBand MCphases in the morphotropic phaseboundary region of (1-x) Pb(Mg1/3Nb2/3)O3-xPbTiO3: A Rietveld study. Phys Rev B,2003,67:064102
[216] Zhai H Y, Rusakova I, Fairhurst R, et al. Different relaxation mechanisms of epitaxialstrain in YBa2Cu3O7-δfilms deposited on SrTiO3and LaAlO3. Philos Mag Lett,2001,81:683-690.
[217] Aindow M, Norris D J, Cheng T T. Misfit dislocations in laser-ablated heteroepitaxialYBa2Cu3O7-δon MgO(001). Philos Mag Lett,1996,74:267-272.
[218] Jia C L, Soltner H, Kabius B, et al. A study of antiphase boundaries and223planarfaults in epitaxial YBa2Cu3O7films by high-resolution electron microscopy. Physica C,1991,182:163-170.
[219] Lian J, Yao H B, Shi D L, et al. Structural characterization of epitaxial YBCO thinfilms prepared by a fluorine-free sol-gel method for coated conductors. Supercond SciTechnol,2003,16:838-844.
[220] Mori N, Teranishi R, Tada K, et al. Formation of microstructures and continuousheating and time-temperature transformation diagrams of YBa2Cu3O7-xfilm fabricatedby metal organic deposition with trifluoroacetates. Jpn J Appl Phys,2008,47:7131-7135.
[221] Mori N, Maebatake T, Teranishi R, et al. In situ observation and simulation of growthprocess of faceted RE123crystals. Physica C,2010,470:1266-1270.
[222] Karmanenko S F. Influence of growth rate on the structural orientation of YBCOsuperconducting films. Supercond Sci Technol,1999,12:36-44.
[223] Ziese M. Colossal magnetoresistance, half metallicity and spin electronics. Phil TransR Soc Lond A,2000,358:137-150.
[224] Asamitsu A, Tomioka Y, Kuwahara H, et al. Current switching of resistive states inmagnetoresistive manganites. Nature,1997,388:50-52.
[225] Yunoki S, Hu J, Malvezzi A L, et al. Phase separation in electronic models formanganites. Phys Rev Lett,1998,80:845-848.
[226] Uehara M, Mori S, Chen C H, et al. Percolative phase separation underlies colossalmagnetoresistance in mixed-valent manganites. Nature,1999,399:560-563.
[227] Mayr M, Moreo A, Verges J A, et al. Resistivity of mixed-phase manganites. Phys RevLett,2001,86:135-138.
[228] Fath M, Freisem S, Menovsky A A, et al. Spatially inhomogeneous metal-insulatortransition in doped manganites. Science,1999,285:1540-1542.
[229] Renner C, Aeppli G, Kim B G, et al. Atomic-scale images of charge ordering in amixed-valence manganite. Nature,2002,416:518-521.
[230] Zhang L W, Israel C, Biswas A, et al. Direct observation of percolation in a manganitethin film. Science,2002,298:805-807.
[231] Van Tendeloo G, Lebedev O I, Amelinckx S. Atomic and microstructure of CMRmaterials. J Magn Magn Mater,2000,211:73-83.
[232] Li D X, Wang M G, Ye H Q. Characterization of the microstructure in CMR materialsby HREM. J Electron Microsc,2002,51: S271-S278.
[233] Lebedev O I, Van Tendeloo G, Amelinckx S. Misfit accommodation of epitaxialLa1-xAXMnO3(A=Ca, Sr) thin films. Int J Inorg Mater,2001,3:1331-1337.
[234] Lebedev O I, Van Tendeloo G, Amelinckx S, et al. Periodic microtwinning as apossible mechanism for the accommodation of the epitaxial film-substrate mismatchin the La1-xSrxMnO3/SrTiO3system. Philos Mag A,2001,81:797-824.
[235] Lebedev O I, Verbeeck J, Van Tendeloo G, et al. Structure and microstructure ofLa1-xSrxMnO3(x approximate to0.16) films grown on a SrTiO3(110) substrate. PhilosMag A,2001,81:2865-2884.
[236] Fujimoto M, Koyama H, Nishi Y, et al. Crystallographic domain structure of anepitaxial Pr0.7Ca0.3MnO3thin film grown on a SrTiO single crystal substrate. J AmCeram Soc,2007,90:2205-2209.
[237] Zhu Y L, Wang X, Zhuo M J, et al. Dislocations in charge-ordered Pr0.5Ca0.5MnO3epitaxial thin films prepared by a two-step growth technique. Philos Mag Lett,2010,90:323-336.
[238]陈前平.电场对磁性/铁电多铁异质结构磁性调控的研究[博士学位论文].北京：清华大学物理系,2012.
[239] Fukumoto N, Mori S, Yamamoto N, et al. Microscopic electronic phase separation andmetal-insulator transition in Nd0.5Sr0.5MnO3. Phys Rev B,1999,60:12963-12967.