Simin Nie

Observation of Fermi arc and its connection with bulk states in the candidate type-II Weyl semimetal WTe2

Chenlu Wang, Yan Zhang, Jianwei Huang, Simin Nie, Guodong Liu1,∗, Aiji Liang, Yuxiao Zhang, Bing Shen, Jing Liu, Cheng Hu, Ying Ding, Defa Liu, Yong Hu, Shaolong He, Lin Zhao, Li Yu, Jin Hu, Jiang Wei, Zhiqiang Mao, Youguo Shi, Xiaowen Jia, Fengfeng Zhang, Shenjin Zhang, Feng Yang, Zhimin Wang, Qinjun Peng, Hongming Weng, Xi Dai, Zhong Fang, Zuyan Xu, Chuangtian Chen and X. J. Zhou1,5,∗ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA Military Transportation University, Tianjin 300161, China. Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China. Collaborative Innovation Center of Quantum Matter, Beijing 100871, China. These people contributed equally to the present work. ∗Corresponding author: gdliu arpes@iphy.ac.cn, XJZhou@iphy.ac.cn.

Observation of Fermi-Arc Spin Texture in TaAs

We have investigated the spin texture of surface Fermi arcs in the recently discovered Weyl semimetal TaAs using spin- and angle-resolved photoemission spectroscopy. The experimental results demonstrate that the Fermi arcs are spin polarized. The measured spin texture fulfills the requirement of mirror and time-reversal symmetries and is well reproduced by our first-principles calculations, which gives strong evidence for the topologically nontrivial Weyl semimetal state in TaAs. The consistency between the experimental and calculated results further confirms the distribution of chirality of the Weyl nodes determined by first-principles calculations.

Electronic evidence of temperature-induced Lifshitz transition and topological nature in ZrTe 5

The topological materials have attracted much attention for their unique electronic structure and peculiar physical properties. ZrTe5 has host a long-standing puzzle on its anomalous transport properties manifested by its unusual resistivity peak and the reversal of the charge carrier type. It is also predicted that single-layer ZrTe5 is a two-dimensional topological insulator and there is possibly a topological phase transition in bulk ZrTe5. Here we report high-resolution laser-based angle-resolved photoemission measurements on the electronic structure and its detailed temperature evolution of ZrTe5. Our results provide direct electronic evidence on the temperature-induced Lifshitz transition, which gives a natural understanding on underlying origin of the resistivity anomaly in ZrTe5. In addition, we observe one-dimensional-like electronic features from the edges of the cracked ZrTe5 samples. Our observations indicate that ZrTe5 is a weak topological insulator and it exhibits a tendency to become a strong topological insulator when the layer distance is reduced.

Quantum spin Hall effect in two-dimensional transition-metal dichalcogenide haeckelites

By using first-principles calculation, we have found that a family of 2D transition metal dichalcogenide haeckelites with square-octagonal lattice

Evidence for Topological Edge States in a Large Energy Gap near the Step Edges on the Surface ofZrTe5

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Observation of anomalous temperature dependence of spectrum on small Fermi surfaces in a BiS2-based superconductor

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Spontaneous Formation of a Superconductor-Topological Insulator-Normal Metal Layered Heterostructure.

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Optical spectroscopy study of Nd(O,F)BiS2 single crystals

=Mo, W and

Raman scattering investigation of the electron-phonon coupling in superconducting Nd(O,F)BiS2

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Electronic structure of SrSn 2 As 2 near the topological critical point

=S, Se and Te) can host quantum spin hall effect. The phonon spectra indicate that they are dynamically stable and the largest band gap is predicted to be around 54 meV, higher than room temperature. These will pave the way to potential applications of topological insulators. We have also established a simple tight-binding model on a square-like lattice to achieve topological nontrivial quantum states, which extends the study from honeycomb lattice to square-like lattice and broads the potential topological material system greatly.