单层MnCoGa中体自旋轨道转矩的对称性依赖极性反转
Symmetry-Dependent Polarity Reversal of Bulk Spin-Orbit Torque in Single-Layer MnCoGa
- Institute of Semiconductors, Chinese Academy of Sciences（中国科学院半导体研究所）
- Université de Lorraine（洛林大学）
- University of Electronic Science and Technology of China（电子科技大学）
- Beihang University（北京航空航天大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
研究在单层MnCoGa赫斯勒合金中实现体自旋轨道转矩，发现其极性反转源于晶格畸变诱导的对称性破缺而非自旋霍尔电导率符号变化，确立应变调控对称性为体SOT调控的新自由度。
AI中文摘要：
控制自旋轨道转矩（SOT）的大小与极性对于自旋电子器件中的磁化操控至关重要。本研究在单层Mn₁.₆Co₁.₄Ga（MCG）赫斯勒合金中实现了体自旋轨道转矩（SOT），并达成了晶格应变调控的SOT极性反转。在3-20 nm的厚度范围内，SOT驱动的磁化翻转均可实现，且翻转极性在强应变超薄 regime 与较厚薄膜之间发生反转。第一性原理计算显示，MCG因拓扑能带结构产生了可观的内禀自旋霍尔电导率（SHC），该电导率因四方畸变而增强，但符号不变。结合厚度依赖的结构演化，研究证实SOT极性反转并非源于SHC的符号变化，而是由晶格畸变诱导的对称性破缺改变了自旋电流向净体SOT的转换过程，进而调控其极性。这些结果确立了应变调控的结构对称性作为调控磁性单层中体SOT的额外自由度。
英文摘要：
Controlling the magnitude and polarity of spin-orbit torque (SOT) is essential for manipulating magnetization in spintronic devices. Here, we realize bulk spin-orbit torque (SOT) in a single-layer Mn1.6Co1.4Ga (MCG) Heusler alloy and achieve lattice strain-controlled reversal of SOT polarity. SOT-driven magnetization switching is achieved over a thickness range of 3-20 nm, with the switching polarity reversed between the strongly strained ultrathin regime and thicker films. First-principles calculations reveal a sizable intrinsic spin Hall conductivity (SHC) in MCG originating from its topological band structure, which is enhanced by the tetragonal distortion without changing sign. Together with the thickness-dependent structural evolution, we demonstrate that the reversal of SOT polarity does not originate from a sign change of the SHC, but rather from lattice distortion induced symmetry breaking that modifies the conversion of spin current into a net bulk SOT, thereby controlling its polarity. These results establish strain-controlled structural symmetry as an additional degree of freedom for tuning bulk SOT in magnetic single layers.
