TM掺杂的Ⅲ-Ⅴ族稀磁半导体电磁性质的第一原理计算

使用基于自旋局域密度泛函理论的第一性原理方法对3d过渡金属(TM=V，Cr，Mn，Fe，Co和Ni)掺杂的Ⅲ-Ⅴ族半导体(GaAs和GaP)的电磁性质进行了计算.结果发现：用V，Cr和Mn掺杂时体系将出现铁磁状态，而Fe掺杂时将出现反铁磁状态，Co和Ni掺杂时，其磁性则不稳定.其中，Cr掺杂的GaAs和GaP将可能是具有较高居里温度的稀磁半导体(DMS).在这些DMS系统中，V离子的磁矩大于理论期待值，Fe，Co和Ni离子的磁矩小于理论期待值，Cr和Mn离子的磁矩与期待值的差距取决于晶体的对称性以及磁性离子的能带分布.此外，使用Si和Mn共同对Ⅲ-Ⅴ族半导体进行掺杂，将有利于DMS表现为铁磁状态，并可以使体系的T_C进一步提高. 关键词： 稀磁半导体 过渡金属 掺杂 共掺杂

Electronic and magnetic properties of 3d transition-metal-doped Ⅲ- Ⅴ semiconductors: first-principle calculations

A systematic study based on ab initio calculations within the local spin density approximation (LSDA) has been performed on the Ⅲ-Ⅴ semiconductors (GaAs and GaP) doped by the 3d-transition metals (TM=V, Cr, Mn, Fe, Co and Ni). It is shown that the ferromagnetic (FM) state will be realized when the GaAs and GaP are doped by V, Cr or Mn, however, the system is antiferromagnetic (AFM) when doped by Fe; whereas these dilute magnetic semicondutors(DMS's) show unstable magnetism when doped by Co or Ni. It is suggested that Ⅲ-Ⅴ semiconductors doped by Cr can be candidates for high Curie Temperature DMS. For the present systems, the magnetic moment of V ion is greater than the theoretical value, those of Fe, Co and Ni are smaller than theoretical values, whereas for those of Cr and Mn, the difference between TM's magnetic moment and the expected value depends on the crystal symmetry and electronic states of ions. Finally, we show that, by the co-doping of Si and Mn in GaAs and GaP, the DMS's present a more stable FM state and a higher T_C.