基于赫斯勒合金Co2MnSi电极的磁性隧道结呈现巨磁阻效应

本文基于电子密度泛函理论计算和非平衡态格林函数技术研究了具有三明治结构的磁性隧道结构(非极化SrTiO₂薄层被夹在两个赫斯勒合金Co₂MnSi电极之间)的自旋极化输运特性. 理论计算结果清楚地表明磁平行组态的磁性隧道结呈现出几乎完美的自旋过滤效应. 磁反平行组态的隧穿系数比磁平行组态的隧穿系数小几个数量级，导致体系的磁阻比高达10⁶. 电子结构计算分析表明该磁性隧道结的巨磁阻效应源自赫斯勒合金Co₂MnSi电极内在的半金属性、以及阻挡层和电极之间界面处过渡金属原子3d电子的显著自旋极化.

Huge Tunneling Magnetoresistance in Magnetic Tunnel Junction with Heusler Alloy Co2MnSi Electrodes

Magnetic tunnel junction with a large tunneling magnetoresistance has attracted great attention due to its importance in the spintronics applications. By performing extensive density functional theory calculations combined with the nonequilibrium Green''s function method, we explore the spin-dependent transport properties of a magnetic tunnel junction, in which a non-polar SrTiO₃ barrier layer is sandwiched between two Heusler alloy Co₂MnSi electrodes. Theoretical results clearly reveal that the near perfect spin-filtering effect appears in the parallel magnetization configuration. The transmission coefficient in the parallel magnetization con guration at the Fermi level is several orders of magnitude larger than that in the antiparallel magnetization configuration, resulting in a huge tunneling magnetoresistance (i.e.>10⁶), which originates from the coherent spin-polarized tunneling, due to the half-metallic nature of Co₂MnSi electrodes and the signifiant spin-polarization of the interfacial Ti 3d orbital.