GaAs掺Mn材料的局域电子结构和磁性

运用原子团模型研究了稀磁半导体GaAs掺Mn的局域电子结构和磁性,计算采用基于密度泛函理论的离散变分方法.计算结果表明Mn原子磁矩随掺杂浓度没有明显的变化,磁矩的数值与实验符合的较好.在包含两个Mn原子的体系中Mn原子之间是铁磁性偶合,表明体系具有铁磁性基态,每个Mn原子的磁矩与掺杂一个Mn原子时相近.对于不同的掺杂浓度,Mn原子与最近邻As原子之间均为反铁磁偶合,Mn原子的3d电子与As原子的4p电子之间有很强的杂化.     

Structural, electronic, and magnetic properties of CrN under high pressure

The structural,electronic and magnetic properties of CrN under high pressure are investigated by first-principles calculations.The antiferromagnetic orthorhombic structure is identified to be the preferred ground state structure.It possesses a bulk modulus of 252.8 GPa and the nonzero magnetic moment of 2.33 μ B per Cr ion,which agree well with the experimental results.CrN undergoes structural and magnetic transitions from an antiferromagnetic rocksalt structure to a non-magnetic Pnma phase at 132 GPa.Under compression,the magnetic moment of the Cr ion reduces rapidly near the equilibrium and phase transition point,and the distribution of the density of states is broadened,but the form of overlap between the orbitals of Cr d and N p remains unchanged.The broadening of the band induces spin flipping,which consequently results in the smaller magnetic moment of the Cr ion.