de Haas–van Alphen oscillation reveals nontrivial Fermi surface topology in Kagome superconductor CsTi3Bi5

Abstract

Abstract The Kagome lattice, naturally encompassing Dirac fermions, flat bands, and van Hove singularities, tends to intertwine exotic electronic states. Revealing the characteristics of its Fermi surface will help on clarifying the nature of the complex quantum phenomena in kagome material. Here we report the Fermi surface properties of the new kagome superconductor CsTi3Bi5 by the de Haas–van Alphen oscillations. The observed oscillations are clear and consist of six principal frequencies ranging from 214 T to 1013 T. The angular dependence of the frequency implies a quasi-two-dimensional electronic structure. In addition, the Berry phase corresponding to 281 T, determined by the Landau level fan diagram method and full Lifshitz-Kosevich formula fitting, yields a value close to π, which indicates a band structure with nontrivial topological property. These results underscore the potential of CsTi3Bi5 as a promising new platform to explore the interplay between topological order, electronic nematicity, and superconductivity.