Polymorphic Layered MoTe2 from Semiconductor, Topological Insulator, to Weyl Semimetal
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- 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 2<i>H-i> and 1<i>Ti>′-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(<i>Ti>), magnetic susceptibility χ(<i>Ti>), and heat capacity <i>Ci>p(<i>Ti>) measurement results reveal a first order structural phase transition near ∼240 K for 1<i>Ti>′-MoTe2, which has been identified to be the orthorhombic <i>Ti>d-phase of MoTe2 as a candidate of Weyl semimetal. The STM study revealed different local defect geometries found on the surface of <i>2Hi>- and <i>Ti>d-types of MoTe6 units in trigonal prismatic and distorted octahedral coordination, respectively.