3C-SiC电子结构和铁磁性的第一性原理研究

First-principles calculations of the electronic structures and ferromagnetism in 3C-SiC

基于第一性原理计算的方法,研究了3C-SiC中缺陷的磁学性质。结果表明,-1价和-2价的硅空位可分别引入3μB和2μB的磁矩,而中性的硅空位却不能引入自发的自旋极化。由于缺陷波函数的扩展性,-2价的硅空位间在距离0.861 6 nm时仍然是长程铁磁耦合的,但-1价的硅空位间是反铁磁耦合,因而该种缺陷对磁性没有贡献。

Based on the first-principles calculations, the magnetic properties of defects in 3C-SiC were studied. Calcula-tions reveal that the single charged silicon vacancy and the double charged silicon vacancy can respectively induce mag-netic moments of 3μB and 2μB;while the neutral one cannot lead to the spontaneous spin polarization. The magnetic coupling between the double charged silicon vacancies is ferromagnetic even when the defect separation is as long as 0. 861 6 nm, which can be explained by the extended tails of defect wave functions;whereas, the single charged silicon vacancies couple antiferromagnetically, which cannot contribute to the magnetism.