涡旋介导的自旋电流注入二维超导体NbSe2
Vortex-mediated spin current injection into two-dimensional superconductor NbSe2
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中文总结 AI 辅助
本研究在NbSe2/LAFO异质结构中实验证实涡旋可介导自旋电流注入，通过热电信号符号反转揭示其机制，为超导自旋电子器件提供新路径。
中文摘要 AI 辅助
将纯自旋电流注入超导体仍然是超导自旋电子学中的一项重大挑战。以往的研究主要集中于自旋极化准粒子和自旋三重态超电流，而涡旋作为第二类超导体中普遍存在的拓扑缺陷，理论上已被提出可作为自旋角动量的替代载体，但直接实验证据仍然缺乏。在此，我们报道了在NbSe2/LiAl2Fe3O8(LAFO)双层结构中涡旋介导的自旋电流注入，这是一种伊辛超导体/亚铁磁绝缘体异质结构。在垂直平面的温度梯度和面内磁场作用下，NbSe2/LAFO双层结构在上临界磁场附近表现出显著的热电峰，其符号与单层NbSe2中观察到的常规涡旋能斯特信号相反。符号反转表明，由自旋电流注入引起的涡旋流动与温度梯度驱动的流动方向相反，这与包括自旋-涡度嬗变和逆涡旋自旋霍尔效应在内的理论机制一致。通过绘制场-温度相图，我们揭示了自旋电流注入仅发生在NbSe2的涡旋液态相中。在超导转变温度以上热电信号的缺失进一步排除了准粒子的贡献。我们的结果确立了涡旋作为超导体中自旋信息的有效载体，为涡旋介导的超导自旋电子器件开辟了新途径。
英文摘要
Injection of pure spin current into superconductors remains a major challenge in superconducting spintronics. Previous studies have primarily focused on spin-polarized quasiparticles and spin-triplet supercurrents, while vortices, ubiquitous topological defects in type-2 superconductors, have been theoretically proposed as alternative carriers of spin angular momentum, yet direct experimental evidence is still lacking. Here, we report the vortex-mediated spin current injection in NbSe2/LiAl2Fe3O8(LAFO) bilayer, an Ising superconductor/ferrimagnetic insulator heterostructure. Under an out-of-plane temperature gradient and an in-plane magnetic field, the NbSe2/LAFO bilayer shows a pronounced thermoelectric peak near the upper critical magnetic field, which has the opposite sign to the conventional vortex Nernst signal observed in a single-layer NbSe2. The sign reversal suggests that the vortex flow induced by spin current injection is opposite to the flow driven by the temperature gradient, which is consistent with theoretical mechanisms including spin-vorticity transmutation and the inverse vortex spin Hall effect. By mapping the field temperature phase diagram, we reveal that the spin current injection occurs exclusively in the vortex liquid phase of NbSe2. Absence of the thermoelectric signal above the superconducting transition temperature further rules out the quasiparticle contribution. Our results establish vortices as efficient carriers of spin information in superconductors, opening a new route towards vortex-mediated superconducting spintronic devices.
发表机构
- Southern University of Science and Technology（南方科技大学）
- Quantum Science Center of Guangdong–Hong Kong–Macao Greater Bay Area (Guangdong)（粤港澳大湾区量子科学中心）
- Guangdong Provincial Key Laboratory of Advanced Thermoelectric Materials and Device Physics（广东省先进热电材料与器件物理重点实验室）
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