Weyl Fermions in VI3 Monolayer.

Taoyuan Jia,Xiaoming Zhang,Xuefang Dai,Guodong Liu,Chunhai Liu,Haopeng Zhang,Weizhen Meng

doi:10.3389/fchem.2020.00722

Abstract

We report the presence of a Weyl fermion in VI3 monolayer. The material shows a sandwich-like hexagonal structure and stable phonon spectrum. It has a half-metal band structure, where only the bands in one spin channel cross the Fermi level. There are three pairs of Weyl points slightly below the Fermi level in spin-up channel. The Weyl points show a clean band structure and are characterized by clear Fermi arcs edge state. The effects of spin-orbit coupling, electron correlation, and lattice strain on the electronic band structure were investigated. We find that the half-metallicity and Weyl points are robust against these perturbations. Our work suggests VI3 monolayer is an excellent Weyl half-metal.

Highlights

We have further investigated the effects of spin-orbit coupling (SOC), electron correlation, and lattice strain on the electronic band structure
We find the Weyl points can exist from 1% compressive stain to 2% tensile strain (Figure 4D). These results show that the half-metal band structure and the Weyl points are in some degree robust against electron correlation effects and lattice strain
We have verified that VI3 monolayer has the ferromagnetic ground state

Summary

Introduction

Weyl semimetals (WSMs) have attracted extensive research attentions (Wan et al, 2011; Lv et al, 2015; Shekhar et al, 2015; Soluyanov et al, 2015; Sun et al, 2015; Weng et al, 2015; Deng et al, 2016; Koepernik et al, 2016; Wu et al, 2016; Kumar et al, 2017). The crossing points, namely, Weyl nodes, appear in pairs with different chirality (Ruan et al, 2016a,b). Such chiral anomaly can induce interesting transport properties such as anomalous Hall effect and negative magnetoresistance (Liu et al, 2013; Son and Spivak, 2013; Liu and Vanderbilt, 2014; Hirayama et al, 2015; Huang et al, 2015). For type II WSMs (Soluyanov et al, 2015; Deng et al, 2016; Koepernik et al, 2016; Wu et al, 2016; Kumar et al, 2017), the Weyl cones are completely tilted. Type II WSMs have different physical phenomena from type I ones, including modified anomalous Hall conductivity, direction-dependent chiral anomaly, and momentum space Klein tunneling (Koshino, 2016; O’Brien et al, 2016; Yu et al, 2016; Zyuzin and Tiwari, 2016)

Methods

Results

Conclusion