Topological insulators have emerged as an important material class for efficient spin-charge interconversion. Most topological insulators considered to date are binary or ternary compounds, with the exception of $\alpha -\mathrm{Sn}$. Here we report a comprehensive characterization of the growth, magnetotransport properties, and current-induced spin-orbit torques of $\alpha -\mathrm{Sn}$ and $\beta -\mathrm{Sn}$-based ferromagnetic heterostructures. We show that $\alpha -\mathrm{Sn}$ grown with a Bi surfactant on CdTe(001) promotes large spin-orbit torques in a ferromagnetic FeCo layer at room temperature, comparable to Pt, whereas $\alpha -\mathrm{Sn}$ grown without Bi surfactant and the nontopological phase, $\beta -\mathrm{Sn}$, induce lower torques. The dampinglike and fieldlike spin-orbit torque efficiency in $\alpha -\mathrm{Sn}$ with Bi are 0.12 and 0.18, respectively. Further, we show that $\alpha -\mathrm{Sn}$ grown with and without Bi presents a spin-Hall-like magnetoresistance comparable to that found in heavy metal/ferromagnet bilayers. Our work demonstrates direct and efficient charge-to-spin conversion in $\alpha -\mathrm{Sn}$ ferromagnetic heterostructures, showing that $\alpha -\mathrm{Sn}$ is a promising material for current-induced magnetization control in spintronic devices.

中文翻译：

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α−Snandβ−Sn 异质结构的自旋轨道扭矩和磁输运特性

拓扑绝缘体已成为有效自旋电荷相互转换的重要材料类别。迄今为止考虑的大多数拓扑绝缘体都是二元或三元化合物，除了$\alpha -锡$. 在这里，我们报告了生长、磁传输特性和电流诱导的自旋轨道扭矩的综合表征$\alpha -锡$ 和 $\beta -锡$基于的铁磁异质结构。我们证明$\alpha -锡$ 在 CdTe(001) 上用 Bi 表面活性剂在室温下促进铁磁 FeCo 层中的大自旋轨道扭矩，与 Pt 相当，而 $\alpha -锡$ 在没有 Bi 表面活性剂和非拓扑相的情况下生长， $\beta -锡$, 引起较低的扭矩。类阻尼和类场自旋轨道转矩效率$\alpha -锡$Bi 分别为 0.12 和 0.18。此外，我们证明$\alpha -锡$有和没有 Bi 生长的磁阻呈现出与重金属/铁磁双层中发现的类似的自旋霍尔磁阻。我们的工作证明了直接有效的电荷到自旋转换$\alpha -锡$ 铁磁异质结构，表明 $\alpha -锡$ 是用于自旋电子器件中电流感应磁化控制的有前途的材料。