AI 中文总结
该研究通过插层破坏反演对称性，设计出4种三维伊辛超导体，其面内上临界场可达泡利极限的4-7倍，确立了插层作为对称性工程策略的潜力。
AI 中文摘要
伊辛超导体的面内上临界场远超泡利顺磁极限，这一特征最初在二维单层过渡金属二硫族化合物（TMD）中被证实。这种场耐受性需要强自旋轨道耦合（SOC）与反演对称性破缺共存，但三维块体实现仍十分稀缺，因为平衡堆叠通常会恢复反演对称性。本文证明插层提供了打破该对称性的实用途径，从四种插层剂（In、Sn、Pb、Bi）中系统设计了16种基于NbSe₂和NbTe₂的化合物，涉及两种多型体：非中心对称的P$\bar{6}$m2和中心对称的P6₃/mmc。P$\bar{6}$m2相的四种化合物InNbSe₂、SnNbSe₂、PbNbSe₂和PbNbTe₂成为有前景的三维伊辛超导体，它们在费米能级附近表现出80-100 meV的SOC分裂、主导的面外自旋极化，以及T_c为2.6-5.4 K的各向异性超导性。值得注意的是，自旋织构分析显示，伊辛保护的效率并非仅由SOC分裂的大小决定，还取决于费米面上的面外自旋纯度。Bogoliubov-de Gennes（BdG）计算预测面内上临界场可达泡利极限的4-7倍。这些发现确立了插层作为在TMD中实现三维伊辛超导体的有前景的对称性工程策略。
英文摘要
Ising superconductors exhibit in-plane upper critical fields far exceeding the Pauli paramagnetic limit, a hallmark first established in two-dimensional (2D) monolayer transition-metal dichalcogenides (TMDs). This field resilience requires the coexistence of strong spin-orbit coupling (SOC) and broken inversion symmetry, yet three-dimensional (3D) bulk realizations remain scarce because equilibrium stacking typically restores inversion symmetry. Here we demonstrate that intercalation provides a practical route to break this symmetry, systematically designing 16 NbSe$_2$- and NbTe$_2$-based compounds from four intercalants (In, Sn, Pb, Bi) across two polytypes: non-centrosymmetric $P\bar{6}m2$ and centrosymmetric $P6_3/mmc$. Four compounds in the $P\bar{6}m2$ phase, InNbSe$_2$, SnNbSe$_2$, PbNbSe$_2$, and PbNbTe$_2$, emerge as promising 3D Ising superconductors. They exhibit SOC splittings of 80-100 meV near the Fermi level, dominant out-of-plane spin polarization, and anisotropic superconductivity with $T_c=2.6$-$5.4$ K. Notably, spin-texture analysis reveals that the efficiency of Ising protection is governed not by the magnitude of SOC splitting alone but by the out-of-plane spin purity on the Fermi surface. Bogoliubov-de Gennes (BdG) calculations predict in-plane upper critical fields reaching 4-7 times the Pauli limit. These findings establish intercalation as a promising symmetry-engineering strategy for realizing 3D Ising superconductors in TMDs.
