CoTiSb基体中Ni元素诱导的单自旋通道研究

Single spin channels in Ni-doped CoTiSb semiconductor

沿半Heusler结构CoTiSb合金的[001]晶体学方向,利用Ni元素连续替换一条原子链上的Ti,Sb原子,在半导体性CoTiSb基体中设计了一系列均匀分布的Ni基单原子链阵列.采用第一性原理方法,研究了Ni基单原子链的电子结构和磁性质,发现Ni-Sb单原子链具有高度自旋极化率和空穴导电特性,Ni-Ti及Ni-Ni单原子链具有100%的自旋极化率,并且在CoTiSb基体中形成了以这种Ni基单原子链为中心的、尺寸非常小的单自旋纳米柱通道.

Since the spin-transfer effect was predicted in 1996, the direct-current-switched magnetic storage has received much attention. A slender nanopillar with high spin-polarized ratio of the conductive electrons is the most favorable for realizing the direct-current-switched magnetic memory. Wang et al.（Sup. Mic. 2015 86 493） showed a supercell idea used to design the nanopillar array in a semiconductor matrix. Based on this idea, in this paper, the Ni-based single atomic chains are designed in the semiconductive Co Ti Sb matrix by continuously substituting Ni for Ti, Sb, or Ti-Sb in the[001] crystallographic direction. These single atomic chains are uniformly distributed in the matrix. We investigate the electronic structures and magnetic properties of Co Ti Sb supercells with the Ni-based single atomic chains by using the first-principle calculations. The calculation results show that the single atomic chains of Ni-Sb（achieved by substituting Ni for Ti） have a high spin polarization and hole conduction properties. The single atomic chain of Ni-Ti（achieved by substituting Ni for Sb） and Ni-Ni single atomic chain（achieved by substituting Ni for Ti and Sb） both have a 100%spin polarization ration at the Fermi level. The Ni-based single atomic chain has an effect on the electronic structures of other atoms surrounding it in about a lattice length and forms a nanopillar with the center of the Ni-based single atomic chain. We predict that Co Ti Sb matrixes with the Ni-Ti and Ni-Ni single atomic chains will be good candidates for the direct-current-switched magnetic storage.