Temperature-Dependent Electronic Structures of TMD Weyl Semimetals
Hsiang-I Huang1, Naoya Kawakami1, Ryuichi Arafune2, Noriaki Takagi3, Chun-Liang Lin1*
1Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
2International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Ibaraki, Japan
3Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan
* Presenter:Chun-Liang Lin, email:clin@nctu.edu.tw
Transition metal dichalcogenides (TMDs) are layered materials with chemical compositions described as MX₂. Here, M represents an element of transition metals and X represents a chalcogen atom. Most TMDs are semiconducting with valley degrees of freedom to generate an application in information processing. On the other hand, MoTe₂ and WTe₂ are semimetallic and have been proposed as candidates for Weyl semimetals [1, 2]. Both have gathered a great deal of attention because the quasiparticles behave as massless chiral fermions −Weyl fermions. One of the unique characteristics of Weyl semimetals is the emergence of a topologically protected surface state called Fermi arc, which can be observed by scanning tunneling microscopy (STM) and angle-resolved angle-resolved photoemission spectroscopy (ARPES).
Recently temperature-dependent transport properties of both WTe₂ [3] and MoTe₂ [4] are reported. Therefore, it is urgent to reveal the temperature-dependent electronic structures of these Weyl Semimetals. By using STM and STM-QPI, both geometric and electronic structures of MoTe₂ and WTe₂ are clearly revealed. Surprisingly, huge variations are found in between the STM-QPI results measured at 5K and 77K. Our results may provide information to explain the temperature-dependent transport properties.
[1] C. L. Lin et al., J. Phys.: Condens. Matter 32, 243001(2020). [2] C. L. Lin et al., ACS Nano 11, 11459 (2017). [3] L. R. Thoutam et al., Phys. Rev. Lett. 115, 046602 (2015). [4] Q. L. Pei et al., Phys. Rev. B 96, 075132 (2017).

Keywords: Weyl semimetals, Temperature-Dependent Properties, Scanning Tunneling Microscopy, Quasiparticle Interferece , Transition metal dichalcogenides