Abstract:
The interplay among frustrated lattice geometry, nontrivial band topology and correlations yields rich quantum states of matter in Kagome systems. A class of recent Kagome metals, AV3Sb5 (A= K, Rb, Cs), exhibit a cascade of symmetry-breaking transitions, involving 3Q chiral charge ordering, electronic nematicity, roton pair density wave and superconductivity. The interdependence among multiple competing orders suggests unconventional superconductivity, the nature of which is yet to be resolved. Here, we report the electronic evidence for chiral superconducting domains with boundary supercurrent, a smoking-gun of chiral superconductivity, in intrinsic Cs V3Sb5 flakes. Magnetic field-free superconducting diode effects are observed with their polarity modulated by thermal histories, suggesting dynamical superconducting order parameter domains in a spontaneous time-reversal-symmetry breaking background. Strikingly, the critical current exhibits double-slit superconducting interference patterns when subjected to external magnetic field. Characteristics of the patterns are modulated by thermal cycling. These phenomena are attributed to the periodic modulation of supercurrent flowing along chiral domain boundaries constrained by fluxoid quantization. Our results provide the direct demonstration of a time-reversal symmetry breaking superconducting order in Kagome systems, opening a potential for exploring exotic physics, e.g. Majorana zero modes, in this intriguing topological Kagome system.
Biography:
Dr. Xiao Lin received his B.S. degree from Zhejiang University (2008), and Ph.D. degree from Zhejiang University (2013). He did his postdoctoral studies at Ecole Supérieure de Physique et de Chimie Industrielles (ESPCI), Paris Tech from 2013 to 2015. He became a Humboldt postdoctoral research fellow at Cologne University from 2016 to 2018. He joined Westlake University as Assistant Professor in March 2018. Dr. Lin has rich experience in studying the transport properties of quantum matter, such as polar superconductors, polar metals, chiral superconductors, etc. His current research interests focus on nonlinear optical/transport phenomena, superconducting diode effect, quantum transport and quantum phase manipulation.
Seminar by the NYU-ECNU Institute of Physics at NYU Shanghai