  We predict through our first-principles calculations that four double
perovskite oxides of Bi2ABO6 (AB = FeMo, MnMo, MnOs, CrOs) are half-metallic
ferrimagnets. Our calculated results shows that the four optimized structures
have negative formation energy, from -0.42 to -0.26 eV per formula unit, which
implies that they could probably be realized. In the case of Bi2FeMoO6, the
half-metallic gap and Curie temperature are predicted to reach to 0.71 eV and
650 K, respectively, which indicates that high spin polarization could be kept
at high temperatures far beyond room temperature. It is believed that some of
them could be synthesized soon and would prove useful for spintronic
applications.
