Half-metallic diluted antiferromagnetic semiconductors

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On the basis of first-principles electronic structure calculations, we have shown that various compounds semiconductors as well as TiO2, chalchopyrite-type compounds doped with more than two kind of magnetic ions such as Cr-Fe and V-Co may exhibit half-metallic antiferromagnetism. We further have calculated the magnetic transition temperature of them materials using the magnetic coupling constants, which are calculated by the Green's function method, combined with a cluster approximation. The results show that the magnetic transition temperature of some half-metallic antiferromagnetic semiconductors will exceeds the room temperature. We also have developed the computer code that enables us to calculate the DC conductivity of these materials using the Kubo-Greenwood formula. Specifically, we have studies the followings:1) We have designed hetero-structures using II-VI compounds half metallic diluted antiferromagnetic semiconductors It was shown that the electron mattering dues to the existence of a possible anti-phase domain boundary might cause GMR effect.2) We have proposed the method to verify the half-metallic antiferromagnetism. On a of the possibility is XMCD and the other is using NMR technique. We actually calculated K-edge XMCD absorption spectra and the hyperfine interactions of probe nuclei in half-metallic antiferromagnets.