发表机构
National Tsing Hua University; National Taiwan University（国立清华大学; 国立台湾大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究针对SOT磁存储器的效率-稳定性权衡问题，开发BCC NiW合金作为自旋电流源，实现超低临界电流密度，兼具高热稳定性，为SOT-MRAM提供了可扩展的材料平台。
AI 中文摘要
高性能自旋轨道转矩（SOT）磁存储器的发展受到传统重金属中自旋霍尔效率、热结构稳定性与垂直磁各向异性之间持续存在的权衡关系的根本限制。在此，我们通过设计体心立方（BCC）掺Ni的W合金作为高效且热稳定的自旋电流源，克服了这一限制。Ni₃₀W₇₀/CoFeB异质结构实现了确定性的面外磁化翻转，其超低临界电流密度为1.78 MA/cm²， nearly threefold lower than that of β-W, while maintaining a high anisotropy field of 8,500 Oe and a thermal stability factor of 57.9. The BCC Ni₃₀W₇₀ alloy preserves its structural integrity and the perpendicular magnetic anisotropy of the adjacent CoFeB layer after annealing at 450 °C, demonstrating robustness under the stringent thermal processing conditions relevant to back-end-of-line integration. Harmonic Hall and ferromagnetic resonance measurements reveal a large spin Hall angle of -0.39 and a high interfacial spin transparency of 0.75, demonstrating efficient spin-current generation and interfacial transmission. First-principles calculations further reveal enhanced intrinsic spin Hall conductivity in W-rich BCC NiW alloys, associated with the Fermi level lying within a spin-orbit-coupling-induced band gap. These findings establish BCC NiW alloys as a scalable and thermally resilient material platform for energy-efficient SOT-MRAM.
英文摘要
The development of high-performance spin-orbit torque (SOT) magnetic memories is fundamentally constrained by a persistent trade-off between spin Hall efficiency, thermal structural stability, and perpendicular magnetic anisotropy in conventional heavy metals. Here, we overcome this limitation by engineering body-centered-cubic (BCC) Ni-doped W alloys as highly efficient and thermally robust spin-current sources. Ni$_{30}$W$_{70}$/CoFeB heterostructures achieve deterministic out-of-plane magnetization switching at an ultra-low critical current density of 1.78 MA/cm$^2$, nearly threefold lower than that of $β$-W, while maintaining a high anisotropy field of 8,500 Oe and a thermal stability factor of 57.9. The BCC Ni$_{30}$W$_{70}$ alloy preserves its structural integrity and the perpendicular magnetic anisotropy of the adjacent CoFeB layer after annealing at 450 $^\circ$C, demonstrating robustness under the stringent thermal processing conditions relevant to back-end-of-line integration. Harmonic Hall and ferromagnetic resonance measurements reveal a large spin Hall angle of -0.39 and a high interfacial spin transparency of 0.75, demonstrating efficient spin-current generation and interfacial transmission. First-principles calculations further reveal enhanced intrinsic spin Hall conductivity in W-rich BCC NiW alloys, associated with the Fermi level lying within a spin-orbit-coupling-induced band gap. These findings establish BCC NiW alloys as a scalable and thermally resilient material platform for energy-efficient SOT-MRAM.
Comments45 pages, 6 figures. Submitted to Nature Communications
