Magnetic structure of GdBiPt: A candidate antiferromagnetic topological insulator

TL;DR

This study investigates GdBiPt, a half-Heusler compound, as a potential antiferromagnetic topological insulator, revealing a layered magnetic structure that could enable non-trivial topological properties through spin-orbit coupling.

Contribution

The paper provides the first experimental characterization of GdBiPt's magnetic structure, supporting its candidacy as an antiferromagnetic topological insulator.

Findings

GdBiPt exhibits ferromagnetic sheets stacked antiferromagnetically.

The magnetic structure may induce spin-orbit coupling effects.

GdBiPt is a promising candidate for topological antiferromagnetism.

Abstract

A topological insulator is a state of matter which does not break any symmetry and is characterized by topological invariants, the integer expectation values of non-local operators. Antiferromagnetism on the other hand is a broken symmetry state in which the translation symmetry is reduced and time reversal symmetry is broken. Can these two phenomena coexist in the same material? A proposal by Mong {\it et al.}\cite{Mong2010} asserts that the answer is yes. Moreover, it is theoretically possible that the onset of antiferromagnetism enables the non-trivial topology since it may create spin-orbit coupling effects which are absent in the non-magnetic phase. The current work examines a real system, half-Heusler GdBiPt, as a candidate for topological anti ferromagnetism. We find that the magnetic moments of the gadolinium atoms form ferromagnetic sheets which are stacked antiferromagnetically along the body diagonal. This magnetic structure may induce spin orbit coupling on band electrons as they hop perpendicular to the ferromagnetic sheets.