三元化合物ZnCrS_2电子结构和半金属铁磁性的第一性原理研究

First-principles study on electronic structure and half-metallic ferromagnetism of ternary compound ZnCrS_2

以闪锌矿相的ZnS2×2×1超原胞为基础,通过将其中的Zn用Cr按1∶1配比进行了a和b两种不同位置的替换构造出了三元化合物ZnCrS2理论模型,然后采用基于密度泛函理论(DFT)的平面波超软赝势(PWPP)方法分别计算了两种不同模型ZnCrS2的电子结构和磁学性质.结果表明,两种模型的ZnCrS2的铁磁态都比反铁磁态更稳定,均是半金属铁磁体(半金属能隙分别为0.9631eV和0.7556eV),其中a位替换不但具有较大的半金属能隙,而且结构更稳定.文中对a位替换结构的自旋极化电子态密度、能带结构、磁矩等进行了详细分析.本文结果可望为实验研究提供指导和理论解释.

The model of the ternary compound ZnCrS2 is constructed by replacing the Zn atoms in the zinc-blend phase ZnS with Cr at two different positions a and b in a ratio of 1∶1. Then the electronic and the magnetic properties of ZnCrS2 are invescigated by using the plane wave pseudopotential （PWPP） method with the density functional theory （DFT）. The results show that both kinds of ZnCrS2 are more stable in the ferromagnetic state than in the anti-ferromagnetic state, and are half-metallic ferromagnets with half-metallic band gaps of 0.964eV and 0.755 eV, respectively. The comparison of two different models reveals that ZnCrS2 in a-position replacement is more sable and also has a larger half-metallic band gap. Furthermore, the spin-polarized electronic density of states, the band structure and the magnetic moment of ZnCrS2 are analyzed in detail. The present results should be useful for the future experimental study.