具有人工单向堆叠层的块体晶体中的伊辛超导和反常金属态
Ising superconductivity and anomalous metallic states in a bulk crystal with artificial unidirectional stacking layers
AI总结：
通过Sr0.75ClNbS2实现单向平行AA堆叠，打破全局反演对称，在块体中获得强伊辛自旋轨道耦合和准二维超导，并发现磁场诱导的反常金属态。
摘要：
宏观块体晶体中的二维极限为探索奇异量子相提供了强大平台。本文报道了Sr0.75ClNbS2超导体的合成，该材料实现了单向、平行的AA堆叠——一种在块体晶体中从未实现的构型。与仅扩大层间距的传统插层不同，我们的方法采用平面Sr-Cl网络强制进行完全的堆叠重组，将所有NbS2层从固有的反平行AB堆叠转变为单向平行AA排列。这种堆叠切换全局地打破了反演对称性，将中心对称的2H-NbS2转变为具有D3h点群对称性的非中心对称块体晶体。关键在于，这种结构设计在三维中再现了孤立单层的电子环境，从而防止了局部伊辛场的抵消。结果，强伊辛自旋轨道耦合和自旋分裂能带在整个块体中持续存在。输运测量揭示了极端的超导各向异性（γ ~ 77）、远超泡利顺磁极限的面内上临界场（~10.65 T）以及表明高晶体质量的清洁极限超导性。此外，磁输运发现了一种新颖的磁场诱导反常金属态，其特征是有限耗散但霍尔响应消失。直接能带结构测量证实了系统的层解耦、准二维电子性质。这项工作确立了堆叠几何工程作为一种强大策略，可人工在块体晶体中强制实现全局非中心对称的准二维超导态，为设计具有可调晶体对称性和电子能带拓扑的量子材料铺平了道路。
英文摘要：
The two-dimensional (2D) limit in macroscopic bulk crystals provides a powerful platform for exploring exotic quantum phases. Here, we report the synthesis of a Sr0.75ClNbS2 superconductor that achieves unidirectional, parallel AA stacking-a configuration never before realized in a bulk crystal. Unlike conventional intercalation, which merely expands the interlayer spacing, our approach employs a planar Sr-Cl network to enforce a complete stacking reorganization, driving all NbS2 layers from the native antiparallel AB stacking into a unidirectional, parallel AA arrangement. This stacking switch globally breaks inversion symmetry, transforming centrosymmetric 2H-NbS2 into a noncentrosymmetric bulk crystal with D3h point group symmetry. Crucially, this structural design reproduces, in three dimensions, the electronic environment of an isolated monolayer, thereby preventing cancellation of the local Ising fields. As a result, strong Ising spin-orbit coupling and spin-split bands persist throughout the bulk. Transport measurements reveal extreme superconducting anisotropy (γ ~ 77), an in-plane upper critical field (~ 10.65 T) that far exceeds the Pauli paramagnetic limit, and clean-limit superconductivity indicative of high crystalline quality. Moreover, magnetotransport uncovers a novel magnetic-field-induced anomalous metallic state characterized by finite dissipation yet a vanishing Hall response. Direct band-structure measurements corroborate the layer-decoupled, quasi-2D electronic nature of the system. This work establishes stacking-geometry engineering as a powerful strategy to artificially enforce a globally noncentrosymmetric, quasi-2D superconducting state in bulk crystals, paving the way for designing quantum materials with tunable crystalline symmetry and electronic band topology.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
