Sun Xikang, Deng Zhengkuan, Yang Yichen, Yu Shuang, Huang Yuqiang, Lu Yunhao, Tao Qian, Shen Da-Wei, He Wen-Yu, Xi Chuanying, Pi Li, Watanabe Kenji, Taniguchi Takashi, Xu Zhu-An, Zheng Yi
School of Physics, and State Key Laboratory of Silicon Materials and Advanced Semiconductor Materials, Zhejiang University, Hangzhou, 310027, China.
State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, Shanghai, 200050, China.
Adv Mater. 2025 Jan;37(4):e2411655. doi: 10.1002/adma.202411655. Epub 2024 Dec 4.
Van der Waals (vdW) crystals with strong spin-orbit coupling (SOC) provide great opportunities for exploring unconventional 2D superconductors, wherein new pairing states emerge due to the interplay of SOC with crystalline symmetries, electronic correlations, quenched disorders and external modulation forces, etc. Here, a distinct mirror-symmetry protected Ising pairing state with unprecedented Γ- and M-valley symmetries in natural vdW heterostructures (vdWH) of interweaving tetragonal SnSe and trigonal 1H-TaSe monolayers is reported, in which the unidirectional lattice interlocking effectively suppresses the K-valley Ising pairing mechanism by incommensurate charge-density-wave (CDW) transitions. In the 2D limit of an TaSe/SnSe bilayer with intact basal mirror symmetry (M), the mirror-symmetric vdWH Ising superconductors show anomalous in-plane magnetic field B-controlled enhancements in the critical temperature T, which is completely absent for multilayer vdWHs with broken M induced by orthorhombic stacking between nearest-neighbour TaSe monolayers. The experimental observations consistently reveal a mirror symmetry-protected type-III Ising state in the inversion asymmetric lattice of 1H-TaSe, which is predicted to be a mixture of spin-singlet and spin-triplet states.
具有强自旋轨道耦合（SOC）的范德华（vdW）晶体为探索非常规二维超导体提供了绝佳机会，在这类超导体中，由于SOC与晶体对称性、电子关联、淬火无序和外部调制力等因素的相互作用，会出现新的配对态。在此，报道了一种在交织的四方相SnSe和三角相1H-TaSe单层的天然vdW异质结构（vdWH）中具有前所未有的Γ谷和M谷对称性的独特镜面对称保护伊辛配对态，其中单向晶格互锁通过非 commensurate电荷密度波（CDW）跃迁有效地抑制了K谷伊辛配对机制。在具有完整基面镜面对称性（M）的TaSe/SnSe双层的二维极限中，镜面对称的vdWH伊辛超导体在临界温度T下表现出异常的面内磁场B控制增强，而对于由最近邻TaSe单层之间的正交堆叠导致M破坏的多层vdWH则完全不存在这种情况。实验观察结果一致揭示了在1H-TaSe的反演不对称晶格中的镜面对称保护III型伊辛态，预计它是自旋单重态和自旋三重态的混合态。
