Half-Heusler合金Cu1-xFexMnSb的电子结构和反铁磁-铁磁相变简

基于密度泛函理论(DFT),使用局域密度近似(LDA)研究了Heusler合金Cu1-xFex MnSb的电子结构和反铁磁-铁磁相变.研究发现,两种磁状态下的合金晶格常数随掺杂浓度x变化很好地满足Vegard定理.当x0.5时,铁磁态合金的总磁矩很好地符合SP规律,然而当x0.5时,却发生了明显的偏离.由于整个体系存在RKKY和超交换磁耦合的竞争,因而在x=0.25时,我们观察到了独特的反铁磁—铁磁相变.进一步的态密度分析发现,Cu的掺杂浓度可以有效调整铁磁态合金的费米面位置,并且反铁磁态合金由于不同自旋方向的Mn原子的分波态密度相互补偿,总态密度形成了几乎完全对称的自旋向上带和自旋向下带.

Electronic structural, magnetic properties and antiferromagnetic-ferromagnetic phase transition

By using local density approach (LDA) within the density functional theory (DFT), we investigate electronic structure and antiferromagnetic(AFM)-ferromagnetic(FM) phase transition of half-Heusler compound Cu1-xFexMnSb. For both FM and AFM states, the calculated lattice constants follow the Vegard law well. In FM state, the total ferromagnetic moment agrees with Slater-Pauling rule as x>0.5 while suffers large deviation as x<0.5. As x=0.25, a novel magnetic phase transition occurs, which mainly derives from the competition between RKKY and superexchange magnetic coupling. Further analyses on density of states (DOS) reveal that the Fermi level can be adjusted by doped Cu concentration in FM state, and d partial DOSs of Mn atoms with different spin orientation compensate for each other that results in the symmetric spin-up and spin-down band in AFM state.