Based on density functional theory (DFT) calculations with a Hubbard $U$-term, we explore the possibility to design an artificial ferrimagnet FeCrO${}_3$ of ilmenite type out of the two antiferromagnets $\alpha$-${\mathrm{Fe}}_2{\mathrm{O}}_3$ and $\alpha$-${\mathrm{Cr}}_2{\mathrm{O}}_3$. By varying the concentration of Fe in $\alpha$-Cr${}_2$O${}_3$, we provide a phase diagram of the relative stability of different chemical and magnetic arrangements with respect to the end members. At $50\%$ Fe-doped $\alpha$-Cr${}_2$O${}_3$, the ilmenite-like structure with alternating Fe and Cr layers and antiparallel magnetic moments competes energetically with a phase-separated structure containing a mixed Fe-Cr interface layer. The magnetic interaction parameters between Fe($3d^5$) and Cr($3d^3$) ions in the digital ferrimagnetic heterostructure, extracted by mapping the DFT total energies to a Heisenberg Hamiltonian, indicate a hematite-like magnetic order with parallel intralayer and antiparallel interlayer alignment.

• Received 23 February 2011

DOI:https://doi.org/10.1103/PhysRevB.83.214424