Magnetic structure of the antiferromagnetic half-Heusler compound NdBiPt

TL;DR

This study investigates the magnetic structure of NdBiPt, revealing a type-I antiferromagnetic order with moments aligned along [001], and suggests it is unlikely to be an antiferromagnetic topological insulator.

Contribution

The paper provides the first detailed neutron diffraction analysis of NdBiPt's magnetic structure, clarifying its AFM order and its incompatibility with AFTI characteristics.

Findings

NdBiPt exhibits AFM transition at 2.18 K.

Magnetic moments align along [001] in a type-I AFM structure.

NdBiPt unlikely to be an antiferromagnetic topological insulator.

Abstract

We present results of single crystal neutron diffraction experiments on the rare-earth, half-Heusler antiferromagnet (AFM) NdBiPt. This compound exhibits an AFM phase transition at $T_{\mathrm N}=2.18$~K with an ordered moment of $1.78(9)$~$\mu_{\mathrm B}$ per Nd atom. The magnetic moments are aligned along the $[001]$-direction, arranged in a type-I AFM structure with ferromagnetic planes, alternating antiferromagnetically along a propagation vector $\tau$ of $(100)$. The $R$BiPt ($R$= Ce-Lu) family of materials has been proposed as candidates of a new family of antiferromagnetic topological insulators (AFTI) with magnetic space group that corresponds to a type-II AFM structure where ferromagnetic sheets are stacked along the space diagonal. The resolved structure makes it unlikely, that NdBiPt qualifies as an AFTI.