Heusler合金Ni_2MnSi的电子结构、磁性、压力响应及四方变形的第一性原理研究

A first-principles study of electronic structure,magnetism,response to pressure and tetragonal distortions of Ni_2MnSi Heusler alloy

运用基于密度泛函理论的第一性原理的投影扩充波函数(PAW)方法,计算了化学计量的Ni2MnSi的晶体结构、磁性、电子结构、压力响应以及四方变形.计算结果表明,在Ni2MnSi的总磁矩中,Mn原子对总磁矩的贡献最大;Ni2MnSi的总态密度的低能部分主要由Si-s投影态密度决定,高能部分主要由Ni-d,Mn-d和Si-p的投影态密度决定;Ni2MnSi在四方变形中,在0.95<c/a<1.15的范围内有一个变化平缓的能量面,这一特性对薄膜的生长和性质有重要意义,预测Ni2MnSi也可以生长出铁磁相的、有较高居里温度的单晶四方结构薄膜.

Crystal structure, magnetism, electronic structure, response to pressure and tetragonal distortions of stoichiometric Ni2 MnSi were calculated by first-principles method based on the density functional theory within the projected augmented wave（PAW） appreach. The calculations show the contribution of the spin magnetic moments of Mn atom to the total moments is largest for Ni2 MnSi. The low energy part of the total DOS is decided by Si-s-projected DOS, however, the high energy part of the total DOS is decided by the Ni -d-projected DOS, Mn -d-projected DOS and Si -p-projected DOS for Ni2MnSi. The entire energy surface for 0.95 〈 c/ a 〈 1.15 is remarkably flat in tetragonal distortions for Ni2 MnSi, which has significant implications for the growth and properties of thin films. We predict that the Ni2MnSi may also grow single crystal tetragonal structured thin film of ferromagnetic phase with high Curie temperature.