Cleaving plane-dependent electronic structures of transition metal diarsenides

Gyanendra Dhakal,Firoza Kabir,Wei-Chi Chiu,Hsin Lin,Sabin Regmi,Arun Bansil,Dariusz Kaczorowski,Bahadur Singh,Baokai Wang,Cheng-Yi Huang,Jonathan Denlinger,Klauss Dimitri,Christopher Sims,William Neff,Madhab Neupane,M Mofazzel Hosen

doi:10.1103/physrevresearch.3.023170

Abstract

Topological Dirac and Weyl semimetals, which support low-energy quasiparticles in condensed matter physics, are currently attracting intense interest due to exotic physical properties such as large magnetoresistance and high carrier mobilities. Transition metal diarsenides such as MoAs2 and WAs2 have been reported to harbor very high magnetoresistance suggesting the possible existence of a topological quantum state, although this conclusion remains dubious. Here, based on systematic angle-resolved photoemission spectroscopy (ARPES) measurements and parallel first-principles calculations, we investigate the electronic properties of TAs2 (T = Mo, W). Importantly, clear evidence for switching the single-Dirac cone surface state in MoAs2 with the cleaving plane is observed, whereas a Dirac state is not observed in WAs2 despite its high magnetoresistance. Our study thus reveals the key role of the terminated plane in a low-symmetry system, and provides a new perspective on how termination can drive dramatic changes in electronic structures.

Highlights

Experimental discovery of a 3D topological insulator state is widely acknowledged as a major milestone in condensed matter and materials physics [1,2,3,4,5]
Since MoAs2 and WAs2 both exhibit metallic band structures at low temperatures with highly populated trivial metallic surface states, our study indicates that topological semimetallic states are not the key for generating high magnetoresistance in these materials
We have carried out a systematic angle-resolved photoemission spectroscopy (ARPES) study of transition-metal diarsenides TAs2 (T = Mo, W) in conjunction with first-principles calculations

Summary

Introduction

Experimental discovery of a 3D topological insulator state is widely acknowledged as a major milestone in condensed matter and materials physics [1,2,3,4,5]. In Dirac semimetals, linearly-dispersing bands cross at low energies and behave like Dirac fermions. Weyl fermions evolve as low-energy excitations at topologically protected crossing points (Weyl nodes) between the electron and hole bands. A recent player on the scene is a type-II Weyl semimetal, which

Methods

Results

Conclusion