过渡金属掺杂SnO2的电子结构与磁性

采用密度泛函理论及赝势平面波方法, 对未掺杂SnO2以及过渡金属V、Cr、Mn掺杂SnO2的超原胞体系进行了几何优化, 计算了晶格常数、电子结构与磁学性质. 结果表明, 6.25%与12.5%两种掺杂浓度时, 体系的电子自旋和磁学性质没有发生很大的变化; 相对于未掺杂SnO2, 过渡金属掺杂后SnO2中O原子有向过渡金属移动的趋势, 并使得O与掺杂金属之间键长变短; 在V和Cr掺杂后, SnO2具有半金属性质, 而Mn掺杂SnO2没有发现上述性质. 6.25%与12.5%的杂质浓度对自旋和磁矩影响不大, 掺杂产生的磁矩主要来自于过渡金属3d电子态, 且磁矩的大小与过渡金属的电子排布有关. V、Cr、Mn掺杂SnO2后的总磁矩分别为0.94μB、2.02μB、3.00μB. 磁矩主要来源于过渡金属3d轨道的自旋极化, 当O原子出现负磁矩的时候, 还有很小一部分磁矩来源于临近过渡金属的Sn原子.

Electronic Structure and Magnetism of Transition Metal Doped SnO2

Based on density functional theory, the geometric structures of SnO2 and transition metal (M) V-, Cr-, and Mn-doped SnO2 were studied by an ultrasoft pseudopotential implemented in the plane wave method. The geometrical parameters, density of states, and magnetic properties were calculated. By comparing two kinds of dopants with concentrations of 6.25% or 12.5%, no significant changes were observed for the electronic and magnetic properties of these systems. The O atom tended to be attracted by the M and the bond distance between O and the metal was shortened. After doping with M, spin polarization appeared near the Fermi surface and the SnO2 doped with V and Cr had a half-metal nature, but the system containing Mn did not show such behavior. The impurity concentration had little effect on the spin and magnetic moment. The magnetic moment of the Mdoped SnO2 mainly originated from the 3d spin polarization and was also related to the electron configuration. The total magnetic moments of the SnO2 doped with V, Cr, and Mn were 0.94μB, 2.02μB, and 3.00μB, respectively. These magnetic moments mainly originate from the 3d spin polarization as some negative moments exist for O and the Sn atomcontributes little to the magnetic moment.