基于PtCr/NiFe的自旋轨道霍尔纳米振荡器
Spin-Orbital Hall Nano-Oscillators using PtCr/NiFe
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中文总结 AI 辅助
该研究利用PtCr/NiFe异质结构，通过合金工程实现巨大自旋轨道转矩，降低自旋轨道霍尔纳米振荡器的阈值电流密度，建立低功耗非线性自旋电子学器件的可扩展材料平台。
中文摘要 AI 辅助
轨道霍尔效应为产生超越传统自旋霍尔物理的角动量电流提供了有前景的途径。PtCr合金表现出异常大的电流诱导转矩，但轨道输运的贡献以及这些转矩维持相干非线性磁化动力学的能力仍未得到解决。本文中，我们利用均质重金属/轻金属合金制备了自旋轨道霍尔纳米振荡器，其中Cr产生的轨道霍尔电流被Pt转换为自旋电流，从而产生巨大的自旋轨道转矩。通过PtCr/NiFe异质结构，尽管Pt被大量稀释，有效转矩效率从Pt/NiFe中的~0.14提升至Pt0.38Cr0.62/NiFe中的~0.40，阈值电流密度从~1.07×10^12 A m^-2降低至~4.4×10^11 A m^-2，实现了相干自激振荡。第一性原理计算表明，Cr合金化抑制了本征自旋霍尔电导率，同时增强了轨道霍尔电导率，且仅当包含轨道输运时才能复现观测到的转矩增强。我们的实验与第一性原理结合结果表明，合金工程可通过本征轨道介导的贡献实现巨大的自旋轨道转矩，无需工程化多层结构即可实现相干自激振荡，为低功耗非线性自旋电子学和轨道电子学器件建立了可扩展的材料平台。
英文摘要
The orbital Hall effect provides a promising route for generating angular-momentum currents beyond conventional spin Hall physics. PtCr alloys exhibit unusually large current-induced torques, but the contribution of orbital transport and the ability of these torques to sustain coherent nonlinear magnetization dynamics remain unresolved. Here we demonstrate spin-orbital Hall nano-oscillators by exploiting a homogeneous heavy-metal/light-metal alloy in which orbital Hall currents generated by Cr are converted by Pt into spin currents, producing giant spin-orbit torques. Using PtCr/NiFe heterostructures, the effective torque efficiency increases from ~0.14 in Pt/NiFe to ~0.40 in Pt0.38Cr0.62/NiFe despite substantial Pt dilution, enabling coherent auto-oscillations with the threshold current density reduced from ~ 1.07 x 10^12 to ~ 4.4 x 10^11 A m^-2. First-principles calculations show that Cr alloying suppresses the intrinsic spin Hall conductivity while enhancing the orbital Hall conductivity, and reproduce the observed torque enhancement only when orbital transport is included. Our combined experimental and first-principles results show that alloy engineering enables giant spin-orbit torques through an intrinsic orbital-mediated contribution, enabling coherent auto-oscillations without engineered multilayers and establishing a scalable materials platform for low-power nonlinear spintronic and orbitronic devices.
