菱面石墨烯中自旋三重态超导的表面选择性探测
Surface-Selective Probe of Spin-Triplet Superconductivity in Rhombohedral Graphene
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中文总结 AI 辅助
本研究以单侧WS₂邻近效应为表面选择性自旋轨道探针，揭示菱面五层石墨烯中含空穴型与电子型载流子的自旋三重态超导，稳定超导态仅在特定位移场符号下存在。
中文摘要 AI 辅助
菱面石墨烯的超导电性已在多种层数中被观测到，越来越多的证据指向自旋三重态配对，但仍缺乏对超导自旋结构的互补探测手段。本研究采用菱面五层石墨烯（R5G）中的单侧WS₂邻近效应作为表面选择性自旋轨道探针：诱导的伊辛自旋轨道耦合对定域在WS₂界面附近的载流子最强，可通过位移场调控超导载流子与自旋轨道扰动的重叠程度。我们观测到高度不对称的超导态：两个稳定的超导 pocket（SC1、SC2）仅在位移场取相反符号时存在，第三个pocket（SC3）则显著更弱。门控特征、量子振荡及自洽能带结构计算确定了相关载流子的层极化与费米面特征；当活性高态密度载流子向WS₂界面极化时，稳定超导态消失或显著减弱。由于伊辛自旋轨道耦合可与时间反演自旋单态配对兼容，但会通过倾斜或钉扎母体自旋结构与同自旋谷间三重态配对竞争，这种表面选择性抑制为涉及空穴型与电子型载流子的自旋三重态超导提供了额外证据。本研究确立了单侧TMD邻近效应作为位移场可调的菱面石墨烯超导自旋结构探针。
英文摘要
Superconductivity in rhombohedral graphene has been observed across many layer numbers, with mounting evidence pointing toward spin-triplet pairing, yet complementary probes of the superconducting spin structure remain needed. Here we use one-sided WS$_2$ proximity in rhombohedral pentalayer graphene (R5G) as a surface-selective spin-orbit probe. The induced Ising spin-orbit coupling is strongest for carriers localized near the WS$_2$ interface, allowing the displacement field to tune the overlap between superconducting carriers and the spin-orbit perturbation. We observe a strongly asymmetric superconducting landscape: two robust pockets, SC1 and SC2, survive only on mutually opposite signs of displacement field, while a third pocket, SC3, is substantially weaker. Gate-tracking features, quantum oscillations, and self-consistent band-structure calculations identify the layer polarization and Fermi-surface character of the relevant carriers. The robust superconducting states are absent or strongly weakened when the active high-DOS carriers are polarized toward the WS$_2$ interface. Since Ising spin-orbit coupling is compatible with time-reversed spin-singlet pairing but competes with same-spin intervalley triplet pairing by canting or pinning the parent spin texture, this surface-selective suppression provides additional evidence for spin-triplet superconductivity involving both hole-like and electron-like carriers. Our results establish one-sided TMD proximity as a displacement-field-tunable probe of superconducting spin structure in rhombohedral graphene.
