Unoccupied electronic structure and signatures of topological Fermi arcs in the Weyl semimetal candidate Mo$_x$W$_{1-x}$Te$_2$

Ilya Belopolski; Su-Yang Xu; Yukiaki Ishida; Xingchen Pan; Peng Yu; Daniel S. Sanchez; Madhab Neupane; Nasser Alidoust; Guoqing Chang; Tay-Rong Chang; Yun Wu; Guang Bian; Hao Zheng; Shin-Ming Huang; Chi-Cheng Lee; Daixiang Mou; Lunan Huang; You Song; Baigeng Wang; Guanghou Wang; Yao-Wen Yeh; Nan Yao; Julien Rault; Patrick Lefevre; François Bertran; Horng-Tay Jeng; Takeshi Kondo; Adam Kaminski; Hsin Lin; Zheng Liu; Fengqi Song; Shik Shin; M. Zahid Hasan

paper

Unoccupied electronic structure and signatures of topological Fermi arcs in the Weyl semimetal candidate Mo $_{x}$ W $_{1 - x}$ Te $_{2}$

arXiv:1512.09099

Abstract

Weyl semimetals have sparked intense research interest, but experimental work has been limited to the TaAs family of compounds. Recently, a number of theoretical works have predicted that compounds in the Mo $_{x}$ W $_{1 - x}$ Te $_{2}$ series are Weyl semimetals. Such proposals are particularly exciting because Mo $_{x}$ W $_{1 - x}$ Te $_{2}$ has a quasi two-dimensional crystal structure well-suited to many transport experiments, while WTe $_{2}$ and MoTe $_{2}$ have already been the subject of numerous proposals for device applications. However, with available ARPES techniques it is challenging to demonstrate a Weyl semimetal in Mo $_{x}$ W $_{1 - x}$ Te $_{2}$ . According to the predictions, the Weyl points are above the Fermi level, the system approaches two critical points as a function of doping, there are many irrelevant bulk bands, the Fermi arcs are nearly degenerate with bulk bands and the bulk band gap is small. Here, we study Mo $_{x}$ W $_{1 - x}$ Te $_{2}$ for $x = 0.07$ and 0.45 using pump-probe ARPES. The system exhibits a dramatic response to the pump laser and we successfully access states $> 0.2$ eV above the Fermi level. For the first time, we observe direct, experimental signatures of Fermi arcs in Mo $_{x}$ W $_{1 - x}$ Te $_{2}$ , which agree well with theoretical calculations of the surface states. However, we caution that the interpretation of these features depends sensitively on free parameters in the surface state calculation. We comment on the prospect of conclusively demonstrating a Weyl semimetal in Mo $_{x}$ W $_{1 - x}$ Te $_{2}$ .

24 pages, 4 figures

Unoccupied electronic structure and signatures of topological Fermi arcs in the Weyl semimetal candidate Mo $_{x}$ W $_{1 - x}$ Te $_{2}$

Abstract

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Unoccupied electronic structure and signatures of topological Fermi arcs in the Weyl semimetal candidate Mox​W1−x​Te2​

Abstract

References in corpus (8)

Cited by in corpus (17)

Unoccupied electronic structure and signatures of topological Fermi arcs in the Weyl semimetal candidate Mo $_{x}$ W $_{1 - x}$ Te $_{2}$