Abstract：
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 (CrI2) on a niobium diselenide (NbSe2) superconductor. Single-layer CrI2 nanosheets, which hold antiferromagnetic (AFM) ground states by our first-principles calculations, were epitaxially grown on the layered NbSe2 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 CrI2 nanosheets. Magnetic-flux vortices induced by an external field exhibit broken 3-fold rotational symmetry of the pristine NbSe2 superconductor, implying the efficient modulation of the interfacial superconducting states by the epitaxial CrI2 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.
摘要：
与超导体耦合的低维磁性结构是实现Majorana零模式的有前途的平台，在拓扑量子计算中具有潜在的应用。这里,我们报告了在二硒化铌（NbSe2）超导体上由单层二碘化铬（CrI2）组成的二维（2D）磁超导异质结构。单层CrI2纳米片，通过我们的第一原理计算保持反铁磁(AFM)基态，在层状NbSe2衬底上外延生长。使用扫描隧道显微镜/光谱学，我们观察到空间上位于纳米片边缘的强健的间隙状态和CrI2纳米片内部的缺陷诱导的零能量峰。由外部场引起的磁通量旋涡表现出原始NbSe2超导体的3重旋转对称性，暗示外延CrI2层对界面超导态的有效调制。现象学模型表明，在具有偶数Chern数的2DAFM-超导混合系统中存在手性边态，为我们的实验观察提供定性的合理理解。
