First-principles study of structural, electronic, and magnetic properties at the (0001)Cr2O3−(111)Pt interface

We perform first-principles density functional calculations to elucidate structural, electronic, and magnetic properties at the interface of $\left(0001\right){\mathrm{Cr}}_2{\mathrm{O}}_3-\left(111\right)\mathrm{Pt}$ bilayers. This investigation is motivated by the fact that, despite the promise of ${\mathrm{Cr}}_2{\mathrm{O}}_3-\mathrm{Pt}$ heterostructures in a variety of antiferromagnetic spintronic applications, many key structural, electronic, and magnetic properties at the ${\mathrm{Cr}}_2{\mathrm{O}}_3-\mathrm{Pt}$ interface are poorly understood. We first analyze all inequivalent lateral interface alignments to determine the lowest energy interfacial structure. For all lateral alignments including the lowest energy one, we observe an accumulation of electrons at the interface between ${\mathrm{Cr}}_2{\mathrm{O}}_3$ and Pt. We find an unexpected reversal of the magnetic moments of the interface Cr ions in the presence of Pt compared to surface Cr moments in vacuum-terminated $\left(0001\right){\mathrm{Cr}}_2{\mathrm{O}}_3$. We also find that the heterostructure exhibits a magnetic proximity effect in the first three Pt layers at the interface with ${\mathrm{Cr}}_2{\mathrm{O}}_3$, providing a mechanism by which the anomalous Hall effect can occur in $\left(0001\right){\mathrm{Cr}}_2{\mathrm{O}}_3-\left(111\right)\mathrm{Pt}$ bilayers. Our results provide the basis for a more nuanced interpretation of magnetotransport experiments on $\left(0001\right){\mathrm{Cr}}_2{\mathrm{O}}_3-\left(111\right)\mathrm{Pt}$ bilayers and should inform future development of improved antiferromagnetic spintronic devices based on the ${\mathrm{Cr}}_2{\mathrm{O}}_3-\mathrm{Pt}$ material system.