Spin-density-functional-based search for half-metallic antiferromagnets

We present results based on local-spin-density calculations of a computational search for half-metallic (HM) antiferromagnetic (Arm) materials within the class of double-perovskite-structure oxides LaM'M"O-3 that incorporate open-shell 3d (or 4d) transition-metal ions M',M". The pairs M'M"=MnCo, CrFe, CrRu, CrNi, MnV, and VCu are studied. Three HM AFM results are found for the (fixed) cubic double perovskite structure. This work provides the first viable candidates for this unusual magnetic phase. La2VMnO6 is the most promising candidate, with the HM AFM phase more stable by 0.17 eV/cell than the ferromagnetic phase. La2VCuO6 is another promising possibility but, because V4+ and Cu2+ are spin-half ions, quantum fluctuations may play an important role in determining the ground state magnetic and electronic structure. This study indicates that HM AFM materials should not be prohibitively difficult to find. [S0163-1829(98)07517-1].