Half-metallic diluted antiferromagnetic semiconductors

在第一性原理电子结构计算的基础上，我们已经证明了各种化合物半导体以及掺杂两种以上磁性离子（如Cr-Fe和V-Co）的TiO2、黄铜矿型化合物可能表现出半金属反铁磁性。利用格林函数法计算的磁耦合常数，结合聚类近似，进一步计算了这两种材料的磁转变温度。结果表明，某些半金属反铁磁半导体的磁转变温度将超过室温。我们还开发了计算机代码，使我们能够使用Kubo-Greenwood公式计算这些材料的直流电导率。具体来说，我们的研究如下：1)我们用II-VI化合物半金属稀释的反铁磁半导体设计了异质结构。结果表明，由于可能存在反相畴边界，电子物质的存在可能导致GMR效应。2)提出了验证半金属反铁磁性的方法。一种可能性是XMCD，另一种是使用核磁共振技术。我们实际计算了半金属反铁磁体中探测核的k边吸收光谱和超精细相互作用。

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.