Weyl Semimetal in a Topological Insulator Multilayer

TL;DR

This paper presents a simple multilayer structure of magnetically-doped topological insulators that realizes a 3D Weyl semimetal phase with unique electronic properties, including chiral edge states and finite anomalous Hall conductivity.

Contribution

It introduces a new multilayer design to realize a minimal Weyl semimetal phase with only two Dirac nodes, bridging insulators and quantum anomalous Hall states.

Findings

Weyl semimetal phase with two Dirac nodes identified in the multilayer system.

Presence of finite anomalous Hall conductivity and chiral edge states.

Weyl semimetal acts as an intermediate phase with metallic behavior at zero temperature.

Abstract

We propose a simple realization of the three-dimensional (3D) Weyl semimetal phase, utilizing a multilayer structure, composed of identical thin films of a magnetically-doped 3D topological insulator (TI), separated by ordinary-insulator spacer layers. We show that the phase diagram of this system contains a Weyl semimetal phase of the simplest possible kind, with only two Dirac nodes of opposite chirality, separated in momentum space, in its bandstructure. This particular type of Weyl semimetal has a finite anomalous Hall conductivity, chiral edge states, and occurs as an intermediate phase between an ordinary insulator and a 3D quantum anomalous Hall insulator with a quantized Hall conductivity, equal to $e^2/h$ per TI layer. We find that the Weyl semimetal has a nonzero DC conductivity at zero temperature and is thus an unusual metallic phase, characterized by a finite anomalous Hall conductivity and topologically-protected edge states.