Li Peigen, Zhang Jihai, Zhu Di, Chen Cui-Qun, Yi Enkui, Shen Bing, Hou Yusheng, Yan Zhongbo, Yao Dao-Xin, Guo Donghui, Zhong Dingyong
School of Physics & Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Sun Yat-sen University, 510275 Guangzhou, China.
State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, 510275 Guangzhou, China.
Nano Lett. 2024 Aug 7;24(31):9468-9476. doi: 10.1021/acs.nanolett.4c01848. Epub 2024 Jul 24.
Low-dimensional magnetic structures coupled with superconductors are promising platforms for realizing Majorana zero modes, which have potential applications in topological quantum computing. Here, we report a two-dimensional (2D) magnetic-superconducting heterostructure consisting of single-layer chromium diiodide (CrI) on a niobium diselenide (NbSe) superconductor. Single-layer CrI nanosheets, which hold antiferromagnetic (AFM) ground states by our first-principles calculations, were epitaxially grown on the layered NbSe substrate. Using scanning tunneling microscopy/spectroscopy, we observed robust in-gap states spatially located at the edge of the nanosheets and defect-induced zero-energy peaks inside the CrI nanosheets. Magnetic-flux vortices induced by an external field exhibit broken 3-fold rotational symmetry of the pristine NbSe superconductor, implying the efficient modulation of the interfacial superconducting states by the epitaxial CrI layer. A phenomenological model suggests the existence of chiral edge states in a 2D AFM-superconducting hybrid system with an even Chern number, providing a qualitatively plausible understanding for our experimental observation.
与超导体耦合的低维磁性结构是实现马约拉纳零模的有前景的平台，马约拉纳零模在拓扑量子计算中有潜在应用。在此，我们报道了一种二维（2D）磁 - 超导异质结构，它由在二硒化铌（NbSe）超导体上的单层二碘化铬（CrI）组成。通过我们的第一性原理计算，单层CrI纳米片具有反铁磁（AFM）基态，其在层状NbSe衬底上外延生长。利用扫描隧道显微镜/光谱，我们观察到在纳米片边缘空间定位的稳健的能隙态以及CrI纳米片内部由缺陷诱导的零能峰。外部磁场诱导的磁通量涡旋表现出原始NbSe超导体的三重旋转对称性破缺，这意味着外延CrI层对界面超导态的有效调制。一个唯象模型表明在具有偶数陈数的二维AFM - 超导混合系统中存在手性边缘态，为我们的实验观察提供了定性合理的理解。
