Epitaxial stabilization of magnetic GdAuSb/LaAuSb superlattices

TL;DR

This paper demonstrates the epitaxial growth of GdAuSb and GdAuSb/LaAuSb superlattices, revealing their structural, electronic, and magnetic properties, and introduces a new platform for tuning magnetic and topological phenomena in rare-earth gold-antimony materials.

Contribution

It reports the first epitaxial stabilization of GdAuSb and superlattices with LaAuSb, providing insights into their structure, electronic bandstructure, and magnetic transitions, enabling control of magnetic and topological order.

Findings

GdAuSb crystallizes in the YPtAs structure type.

Superlattices exhibit sharp interfaces and superlattice fringes.

Two magnetic transitions observed in superlattices.

Abstract

We report the epitaxial stabilization of GdAuSb films and GdAuSb/LaAuSb superlattices via molecular beam epitaxy on (0001)-oriented Al$_{2}$O$_{3}$ substrates. GdAuSb crystallize in the Au-Au dimerized YPtAs structure type (space group $P6_{3}/mmc$), the same structure as the Dirac semimetal LaAuSb. Angle-resolved photoemission spectroscopy (ARPES) measurements show similar near $E_F$ bandstructures for GdAuSb and LaAuSb, plus a rigid band shift for GdAuSb towards more hole-like behavior and core-like Gd $4f$ states $\sim 9$~eV below the Fermi energy. LaAuSb/GdAuSb superlattices exhibit sharp superlattice fringes by X-ray diffraction and atomically-precise interfaces by scanning transmission electron microscopy. Superlattices display two transitions in temperature-dependent resistvity, compared to a single N\'{e}el temperature for thick GdAuSb films. Superlattices of $Ln$AuSb materials ($Ln=$ rare earth) with atomically abrupt interfaces offer a new epitaxial platform for control of magnetic and topological order via tunable intralayer exchange and reduced dimensionality.