Exotic superconductivity in new topological kagome metal CsTi₃Bi₅

【摘要】 We present a systematic investigation of the superconductivity in high-quality CsTi₃Bi₅ single crystals by combining bulk property characterization and local-probe spectroscopy. Two successive superconducting transitions are observed in this newly discovered kagome material. In the first stage, the diamagnetic response strengthens significantly from T_c ～4.9 K to 4.6 K, followed by a broad transition below 4.6 K in the second stage. Moreover, different magnetic field dependences are observed for the two stages, where the first stage is field-insensitive while the second stage exhibits strong field dependence.The ultra-low magnetic field measurements indicate that the lower critical field H_c1（T） exhibits small anisotropy. Based on a comparative study of the superconducting state in CsBi2 and microscopic verification via scanning tunneling microscopy（STM）, our results suggest the emergence of exotic and intrinsic superconductivity in this new titanium-based kagome superconductor, establishing it as a promising platform for further exploring the complexity of electronic states in the kagome lattice.更多还原

【Abstract】 We present a systematic investigation of the superconductivity in high-quality CsTi₃Bi₅ single crystals by combining bulk property characterization and local-probe spectroscopy. Two successive superconducting transitions are observed in this newly discovered kagome material. In the first stage, the diamagnetic response strengthens significantly from T_c ～4.9 K to 4.6 K, followed by a broad transition below 4.6 K in the second stage. Moreover, different magnetic field dependences are observed for the two stages, where the first stage is field-insensitive while the second stage exhibits strong field dependence.The ultra-low magnetic field measurements indicate that the lower critical field H_c1（T） exhibits small anisotropy. Based on a comparative study of the superconducting state in CsBi2 and microscopic verification via scanning tunneling microscopy（STM）, our results suggest the emergence of exotic and intrinsic superconductivity in this new titanium-based kagome superconductor, establishing it as a promising platform for further exploring the complexity of electronic states in the kagome lattice.更多还原