Epitaxial stabilization of magnetic GdAuSb/LaAuSb superlattices

We report the epitaxial stabilization of GdAuSb films and GdAuSb/LaAuSb superlattices via molecular beam epitaxy on (0001)-oriented ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ substrates. GdAuSb crystallizes in the Au-Au dimerized YPtAs structure type (space group $P{6}_{3}/mmc$), 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 toward more holelike behavior and corelike Gd $4f$ states $\ensuremath{\sim}9\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$ 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\'eel temperature for thick GdAuSb films. Superlattices of $Ln\mathrm{AuSb}$ materials ($Ln=$ rare earth) with atomically abrupt interfaces offer an epitaxial platform for control of magnetic and topological order via tunable intralayer exchange and reduced dimensionality.