Half-metallic antiferromagnetic double perovskites: LaAVRuO 6 (A=Ca, Sr, and Ba)

Based on the theoretical exploration of electronic structures, we propose that the ordered double perovskites $\mathrm{La}A{\mathrm{VRuO}}_{6}$ and ${\mathrm{LaVO}}_{3}/A{\mathrm{RuO}}_{3}$ (001) superlattice $(A=\mathrm{Ca},$ Sr, and Ba) are strong candidates for half-metallic (HM) antiferromagnets (AFM's). We have shown that the HM-AFM nature in $\mathrm{La}A{\mathrm{VRuO}}_{6}$ is very robust regardless of (i) divalent ion replacement at A sites, (ii) oxygen site relaxation, (iii) the inclusion of the Coulomb correlation, and (iv) cation disorder. A type of the double exchange interaction is expected to be responsible for the half-metallicity and the antiferromagnetism in these systems.