Fermi surface mapping of the kagome superconductor RbV3Sb5 using de Haas-van Alphen oscillations

Abstract

We present the results from torque magnetometry studies of the kagome superconductor RbV3Sb5 under applied fields up to 45 T and temperatures down to liquid 3 He temperature (0.32 K). The torque signal shows clear de Haas-van Alphen (dHvA) oscillations with eight distinct frequencies ranging from ∼ 150 T to 3000 T. Among these, five are above 500 T. Angle-dependent measurement of dHvA shows that all frequencies follow 1/cosθ dependence, where θ is the tilt angle with respect to the applied field direction, and the oscillations disappear above θ = 60 o , which confirms that the Fermi surfaces corresponding to these frequencies are two dimensional. The Berry phase (φ), calculated by constructing a Landau level fan diagram, is found to be ∼ π, which strongly supports the non-trivial topology of RbV3Sb5. Using the Lifshitz-Kosevich formula, we estimate the effective mass (m * ) of charge carriers in RbV3Sb5, and it is found to be heavier (∼ 0.7mo, where mo is the free electron mass) than that for other topological insulators. The findings of high frequencies up to 3000 T in RbV3Sb5 have not been reported previously, and the results regarding the Fermi surface of RbV3Sb5 are crucial for understanding the charge density wave order, superconductivity, and non-trivial topology in AV3Sb5 (A = K, Rb, and Cs), as well as the interplay among them.