Topological Phase and Quantum Anomalous Hall Effect in Ferromagnetic Transition-Metal Dichalcogenides Monolayer 1T-VSe2.

Angus Huang,Horng-Tay Jeng,Ching-Hao Chang,Chin-Hsuan Chen

doi:10.3390/nano11081998

Abstract

Magnetic two-dimensional (2D) van der Waals materials have attracted tremendous attention because of their high potential in spintronics. In particular, the quantum anomalous Hall (QAH) effect in magnetic 2D layers shows a very promising prospect for hosting Majorana zero modes at the topologically protected edge states in proximity to superconductors. However, the QAH effect has not yet been experimentally realized in monolayer systems to date. In this work, we study the electronic structures and topological properties of the 2D ferromagnetic transition-metal dichalcogenides (TMD) monolayer by first-principles calculations with the Heyd–Scuseria–Ernzerhof (HSE) functional. We find that the spin-orbit coupling (SOC) opens a continuous band gap at the magnetic Weyl-like crossing point hosting the quantum anomalous Hall effect with Chern number . Moreover, we demonstrate the topologically protected edge states and intrinsic (spin) Hall conductivity in this magnetic 2D TMD system. Our results indicate that monolayer serves as a stoichiometric quantum anomalous Hall material.

Highlights

Topological phase has been one of the main themes in solid-state physics and materials science in the past decade
We propose that 1T − VSe2 monolayer is a quantum anomalous Hall (QAH) semimetal with the same Hall conductivity and spin Hall conductivity, i.e., the same charge Hall current and spin Hall current
The Heyd–Scuseria– Ernzerhof (HSE) hybrid exchange-correlation functional demonstrate a topological phase with Chern number C = 2 in 1T − VSe2 monolayer, resulting in a 2D QAH semimetal

Summary

Introduction

Topological phase has been one of the main themes in solid-state physics and materials science in the past decade. Since the study of graphene, Haldane shows that the Landau level can be presented in graphene if including an external term [1] such as the spin-orbital coupling (SOC), which is known as the quantum spin Hall effect or Z2 topological insulators [2]. The discovery of tuning topological phases, whether through spin-orbital coupling (HgTe quantum well state [3] and Bi2 Te3 [4]), electron–phonon coupling (BiTeI [5]), ion doping (WTe2 [6]), and external strain (Bi2 Se3 [7], HgSe monolayer [8]), has opened new routes to control phases and transport properties.

Methods

Discussion

Conclusion