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

• DOI: 10.48550/arxiv.1512.09099
• Publication Date: 2015-01-01
• Authors: Ilya Belopolski; Su‐Yang Xu; Y. 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 Young Song; Baigeng Wang; Guanghou Wang; Yao‐Wen Yeh; Nan Yao; Julien Rault; Patrick Lefèvre; F. Bertran; Horng‐Tay Jeng; Takeshi Kondo; Adam Kaminski; Hsin Lin; Zheng Liu; Fengqi Song; Shik Shin; M. Zahid Hasan
• Keywords: Weyl semimetal

Weyl semimetals have sparked intense research interest, but experimental work has been limited to the TaAs family of compounds. Recently, a number theoretical works predicted that compounds in Mo$_x$W$_{1-x}$Te$_2$ series are semimetals. Such proposals particularly exciting because quasi two-dimensional crystal structure well-suited many transport experiments, while WTe$_2$ and MoTe$_2$ already subject numerous for device applications. However, with available ARPES techniques it is challenging demonstrate semimetal Mo$_x$W$_{1-x}$Te$_2$. According predictions, points above Fermi level, system approaches two critical as function doping, there irrelevant bulk bands, arcs nearly degenerate bands band gap small. Here, we study $x = 0.07$ 0.45 using pump-probe ARPES. The exhibits dramatic response pump laser successfully access states $> 0.2$eV level. For first time, observe direct, signatures Mo$_x$W$_{1-x}$Te$_2$, which agree well calculations surface states. caution interpretation these features depends sensitively on free parameters state calculation. We comment prospect conclusively demonstrating