Tunable Cobalt Vacancies and Related Properties in LaCoxAs2

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• 作者：Shijie Shen ; Gang Wang ; Shifeng Jin ; Qingzhen Huang ; Tianping Ying ; Dandan Li ; Xiaofang Lai ; Tingting Zhou ; Han Zhang ; Zhiping Lin ; Xiaozhi Wu ; Xiaolong Chen
• 刊名：Chemistry of Materials
• 出版年：2014
• 出版时间：November 11, 2014
• 年：2014
• 卷：26
• 期：21
• 页码：6221-6225
• 全文大小：321K
• ISSN：1520-5002

文摘

The origin of transition metal vacancies and their effects on the properties of ThCr₂Si₂-type compounds have been less studied and poorly understood. Here we carefully investigate the structure, physical properties, and electronic structure for a series of lanthanum cobalt arsenides with nominal composition of LaCo_xAs₂ (1.6 鈮?x 鈮?2.1). It is revealed that the occupancy of Co can be tuned between 1.98(1) and 1.61(1). The structural analyses based on X-ray and neutron diffractions show the existence of Co vacancies results from charge balance due to the formation of bond between As鈥揂s. These Co vacancies affect the magnetic and electrical properties greatly, adjusting the Curie temperature from 205 to 47 K and increasing the resistivity by more than 100%. First-principles calculations indicate that the Co vacancies weaken the spin polarization and reduce the density of states at the Fermi level, resulting in decreased Curie temperature and increased resistivity, respectively. Our results address the importance of transition metal vacancies in ThCr₂Si₂-type materials and offer a reliable route to tune the magnetism of ThCr₂Si₂-type structure.