Polymorphic Layered MoTe2 from Semiconductor, Topological Insulator, to Weyl Semimetal

详细信息    查看全文

• 作者：Raman SankarG. Narsinga Rao ; I. Panneer Muthuselvam ; Christopher Butler ; Nitesh Kumar ; G. Senthil Murugan ; Chandra Shekhar ; Tay-Rong Chang ; Cheng-Yen Wen ; Chun-Wei Chen ; Wei-Li Lee ; M.-T. Lin ; Horng-Tay Jeng ; Claudia Felser ; F. C. Chou
• 刊名：Chemistry of Materials
• 出版年：2017
• 出版时间：January 24, 2017
• 年：2017
• 卷：29
• 期：2
• 页码：699-707
• 全文大小：699K
• ISSN：1520-5002

文摘

Large size (∼2 cm) single crystals of layered MoTe₂ in both 2H- and 1T′-types were synthsized using TeBr₄ as the source of Br₂ transport agent in chemical vapor transport growth. The crystal structures of the as-grown single crystals were fully characterized by X-ray diffraction, Raman spectroscopy, scanning transmission electron microscopy, scanning tunneling microscopy (STM), and electrical resistivity (ρ) measurements. The resistivity ρ(T), magnetic susceptibility χ(T), and heat capacity C_p(T) measurement results reveal a first order structural phase transition near ∼240 K for 1T′-MoTe₂, which has been identified to be the orthorhombic Td-phase of MoTe₂ as a candidate of Weyl semimetal. The STM study revealed different local defect geometries found on the surface of 2H- and Td-types of MoTe₆ units in trigonal prismatic and distorted octahedral coordination, respectively.