MoSe$_2$/CrI$_3$和WSe$_2$/CrI$_3$范德华异质结中带内输运驱动的非线性自旋轨道转矩工程
Engineering nonlinear spin-orbit torque driven by intra-band transport in MoSe$_2$/CrI$_3$ and WSe$_2$/CrI$_3$ van der Waals heterostructures
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中文总结 AI 辅助
本研究通过理论分析揭示TMDC/CrI$_3$异质结中非线性带内跃迁主导的自旋轨道转矩，发现其符号和大小受化学势、掺杂及材料调控，为超薄低功耗自旋电子器件提供新平台。
中文摘要 AI 辅助
在范德华磁性异质结构中，非线性载流子动力学在电流驱动自旋现象中的作用仍知之甚少。在此，我们研究了过渡金属二硫族化物/碘化铬（TMDC/CrI$_3$）异质结中的自旋极化及由此产生的自旋轨道转矩（SOT），重点关注WSe$_2$/CrI$_3$和MoSe$_2$/CrI$_3$，在零Rashba自旋轨道耦合（SOC）极限及线性响应 regime 之外。我们发现线性自旋极化被对称性禁止，使得非线性带内跃迁成为该 regime 中的主导机制。因此，电流驱动的自旋响应与常规线性响应预测根本不同。由此产生的非线性自旋极化生成纯类场转矩，其大小和符号敏感地依赖于化学势和掺杂类型，在n型和p型掺杂系统之间表现出显著的不对称性。还观察到强烈的材料依赖性：n型掺杂的MoSe$_2$/CrI$_3$表现出比WSe$_2$/CrI$_3$大近一个数量级的转矩，并伴有两次符号反转，反映了它们SOC和近邻交换参数的差异。通过扭转角和栅极电场进行的结构和静电控制提供了调节非线性转矩的额外手段，包括显著调制和可控的符号反转。这些发现确立了TMDC/CrI$_3$双层结构作为在超薄、低功耗自旋电子器件中工程非线性自旋轨道现象的通用平台。
英文摘要
The role of nonlinear carrier dynamics in current-driven spin phenomena remains poorly understood in van der Waals magnetic heterostructures. Here, we investigate the spin polarization and the resulting spin-orbit torque (SOT) in transition-metal dichalcogenide/chromium iodide (TMDC/CrI$_3$) heterostructures, focusing on WSe$_2$/CrI$_3$ and MoSe$_2$/CrI$_3$, in the zero-Rashba spin-orbit coupling (SOC) limit and beyond the linear-response regime. We find that linear spin polarization is forbidden by symmetry, making nonlinear intraband transitions the dominant mechanism in this regime. Consequently, the current-driven spin response differs fundamentally from conventional linear-response predictions. The resulting nonlinear spin polarization generates a purely field-like torque whose magnitude and sign depend sensitively on the chemical potential and doping type, with pronounced asymmetries between n- and p-doped systems. A strong material dependence is also observed: n-doped MoSe$_2$/CrI$_3$ exhibits a torque nearly an order of magnitude larger than that of WSe$_2$/CrI$_3$, together with two sign reversals, reflecting differences in their SOC and proximity-exchange parameters. Structural and electrostatic control through the twist angle and gate electric field provides additional means of tuning the nonlinear torque, including substantial modulation and controllable sign reversals. These findings establish TMDC/CrI$_3$ bilayers as a versatile platform for engineering nonlinear spin-orbit phenomena in ultrathin, low-power spintronic devices.
发表机构
- Faculty of Science, Department of Physics, Shahid Chamran University of Ahvaz（阿瓦士沙希德·恰姆兰大学理学院物理系）
- School of Quantum Physics and Matter, Institute for Research in Fundamental Sciences (IPM)（基础科学研究所量子物理与物质学院）
- Department of Physics, Zhejiang Normal University（浙江师范大学物理系）
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