Mn掺杂对半金属铁磁体Fe_2Si电磁特性的影响

此文用基于密度泛函理论第一性原理的贋势平面波方法,计算了Fe_2Si及Mn掺杂Fe_2Si体系的能带结构、电子态密度和磁学特性,分析了不同位置Mn掺杂对Fe_2Si电磁特性的影响,获得了纯的和不同位置Mn掺杂的Fe_2Si体系是铁磁体,自旋向上的能带结构穿过费米面表现金属特性,纯Fe_2Si的半金属隙为0.164e V;Mn掺杂在Fe1位时,自旋向下部分转变为A-M间的间接带隙半导体,体系呈现半金属特性,此时磁矩为2.00μB,是真正的半金属性铁磁体;掺杂在Fe2位时,自旋向下部分的带隙值接近于0,体系呈现金属特性;掺杂在Fe3位时,自旋向下部分转变为L-L间的直接带隙半导体,体系呈现半金属特性等有益结果 .自旋电荷密度分布图表明Mn原子的3d电子比较局域,和周围原子成键时3d电子更倾向于形成共价键.体系的半金属性和磁性主要来源于Fe-3d电子与Mn-3d电子之间的d-d交换,Si-3p电子与Fe、Mn-3d电子之间的p-d杂化.这些结果为半金属铁磁体Fe_2Si的电磁调控提供了有效的理论指导.

Effect of Mn-doped on electromagnetic properties of half-metallic ferromagnet Fe2Si

The band structures, electron densities and magnetic properties of Fe2Si and Mn-doped Fe2Si systems have been calculated by the first-principles pseudo-potential method based on density functional theory (DFT). The band structures show that the pure Fe2Si and Fe2Si doped with Mn at Fe1/Fe3 site systems are ferromagnetic which are metal structure under spin-up and semiconductor under spin-down. The system is transformed into metal when Fe2 is the doped site. The spin charge density distribution shows that the 3d electrons of the Mn atoms are localized, and the 3d electrons tend to form covalent bonds with the surrounding atoms. The half-metallic and magnetic properties of the system are mainly derived from the d-d exchange between Fe-3d and Mn-3d electrons, p-d hybridization between Si-3p and Fe/Mn-3d electrons. The results provide effective theoretical guidance for the electromagnetic control of half-metallic ferromagnet Fe2Si.