层状超导电性

中文摘要 AI 辅助

我们识别出一种机制，其中配对凝聚体的软非幺正涨落可以抑制二维Rashba超导体中邻近易平面铁磁序的相位相干性。这种自旋极化通过Lifshitz不变量与超电流线性耦合，充当超导U(1)相位的涌现规范场。积分掉软磁涨落会重整化有效超流刚度，并将系统驱动到“层状”超导态，其特征是有限动量螺旋相位纹理和在一个方向上消失的长波长刚度。因此，涡旋不再具有对数发散的能成本，准长程超导序在任何有限温度下被破坏。弱的晶格各向异性钉扎铁磁序，在长波长处截断层状行为，从而恢复有限的有效刚度。尽管如此，在磁序起始附近，增强的磁化率导致任意弱的磁电耦合下出现涡旋去禁闭区域。这些结果提供了关于交织的超导和易平面铁磁序如何重塑相位相干性的见解，与由过渡金属二硫族化物衬底近邻化的菱面体石墨烯相关。

英文摘要

We identify a mechanism in which soft nonunitary fluctuations of the pair condensate can suppress phase coherence in a two-dimensional Rashba superconductor proximate to easy-plane ferromagnetic order. This spin polarization couples linearly to the supercurrent through a Lifshitz invariant, acting as an emergent gauge field for the superconducting $\mathrm{U}(1)$ phase. Integrating out soft magnetic fluctuations renormalizes the effective superfluid stiffness and drives the system into a "smectic" superconducting state, characterized by a finite-momentum helical phase texture and a long-wavelength stiffness that vanishes in one direction. Consequently, vortices no longer have a logarithmically divergent energy cost, and the quasi-long-range superconducting order is destroyed at any finite temperature. Weak lattice anisotropy pins the ferromagnetic order, cutting off the smectic-like behaviour at long wavelengths and thereby restoring a finite effective stiffness. Nonetheless, near the onset of magnetic order, the enhanced magnetic susceptibility leads to a vortex-deconfined regime for arbitrarily weak magnetoelectric coupling. The results provide insight into how intertwined superconducting and easy-plane ferromagnetic orders can reshape phase coherence, with relevance to rhombohedral graphene proximitized by a transition-metal dichalcogenide substrate.

发表机构

• Johns Hopkins University（约翰斯·霍普金斯大学）
• University of California, Santa Barbara（加州大学圣塔芭芭拉分校）
• Weizmann Institute of Science（魏茨曼科学研究所）

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