半导体ZnS:Co的电子结构与磁性研究

Electronic Structure and Magnetic Properties of Co-Doped ZnS with Zinc Blende Structure

采用基于密度泛函理论的第一性原理方法,研究了闪锌矿结构Co掺杂ZnS体系的电子结构和磁性。通过计算掺杂后组态的几何参数、形成能、磁矩、电子态密度以及电荷密度,发现单个Co原子掺杂,替换超晶胞(2×2×2)中心的Zn原子后体系形成能小于0,可以实现掺杂,且在费米能级处出现自旋极化现象,体系具有半金属特性。通过对2个Co原子的掺杂情况的计算,发现Co-S-Co反铁磁耦合、Co-S-Zn-S-Co铁磁耦合时体系最稳定,同时解释了Co掺杂ZnS体系的铁磁性产生机理。

The electronic structure and magnetic properties of Co-doped ZnS （zinc blende） were studied with the first-principle method using PW91 within the generalized gradient approximation （GGA） for exchange-correlation. Geometric parameters, formation energies, magnetic moments, density of states, and electron charge densities were investigated. It is found that the formation energy is less than 0 as one Co atom is doped into the middle of the super cell （2×2×2）, which indicates that this structure is stable for Co-doping. And the density of states （DOS） near to the Fermi level （Er） indicates the presence of a half-metallic character which is caused by p-d hybridization between the Co 3d and S 3p. When two Co atoms are doped into the ZnS （zinc blende）, antiferromagnetic （AFM） state is the most stable configuration in the system of Co-S-Co. But in the case of Co-S-Zn-S-Co, the most stable configuration is ferromagnetic （FM） state.