论文部分内容阅读
运用第一性原理的方法,研究了磁性形状记忆合金Mn_2NiGa在马氏体相变中晶格结构、磁结构、Mn原子d电子结构的变化.研究表明,伴随Mn_2NiGa马氏体相变的发生,形成了一个由两根长键及四根短键组成的拉长八面体结构,即产生了沿z轴拉长的Jahn-Teller畸变;在相变时,位于八面体中心的Mn原子的磁矩发生显著的变化,而作为配体的Ni、Ga原子的磁矩变化很微小;Jahn-Teller畸变的发生,是由于晶体的畸变使配住场产生变化,导致Mn原子d电子态密度重新分布,从而使e_g和t_(2g)能级分裂所致.
The first order principle is used to study the lattice structure, magnetic structure and electronic structure of Mn atom in the magnetic shape memory alloy Mn_2NiGa during martensitic transformation.The results show that with the occurrence of Mn_2NiGa martensitic transformation, Forming an elongated octahedral structure consisting of two long bonds and four short bonds, resulting in a Jahn-Teller distortion elongated along the z-axis; at the phase transition, the magnetic moment of the Mn atom in the center of the octahedron , The magnetic moment of Ni and Ga atoms as ligands is very small. The Jahn-Teller distortion occurs due to the distortion of the crystal, which leads to the change of the residence field, resulting in the redistribution of the electron density of Mn atoms. Resulting in the cleavage of e_g and t_ (2g) levels.