Topological electronic structure in the antiferromagnet HoSbTe

TL;DR

This paper reports the discovery of topological electronic structures in the antiferromagnetic material HoSbTe, revealing a transition from a Dirac nodal line semimetal to a weak topological insulator due to strong spin-orbit coupling, with potential quantum device applications.

Contribution

It demonstrates the topological nature of HoSbTe and how strong spin-orbit coupling transforms its electronic structure, combining experimental ARPES data with first-principles calculations.

Findings

HoSbTe is a Dirac nodal line semimetal without SOC.

Strong SOC gaps out nodal lines, turning it into a weak topological insulator.

Large energy gaps (~hundreds of meV) observed along specific directions.

Abstract

Magnetic topological materials, in which the time-reversal symmetry is broken, host various exotic quantum phenomena, including the quantum anomalous Hall effect, axion insulator states, and Majorana fermions. The study of magnetic topological materials is at the forefront of condensed matter physics. Recently, a variety of magnetic topological materials have been reported, such as Mn$_3$Sn, Co$_3$Sn$_2$S$_2$, Fe$_3$Sn$_2$, and MnBi$_2$Te$_4$. Here, we report the observation of a topological electronic structure in an antiferromagnet, HoSbTe, a member of the ZrSiS family of materials, by angle-resolved photoemission spectroscopy measurements and first-principles calculations. We demonstrate that HoSbTe is a Dirac nodal line semimetal when spin-orbit coupling (SOC) is neglected. However, our theoretical calculations show that the strong SOC in HoSbTe fully gaps out the nodal lines and drives the system to a weak topological insulator state, with each layer being a two-dimensional topological insulator. Because of the strong SOC in HoSbTe, the gap is as large as hundreds of meV along specific directions, which is directly observed by our ARPES measurements. The existence of magnetic order and topological properties in HoSbTe makes it a promising material for realization of exotic quantum devices.