Dr. Ramakanta Chapai
Norfolk State University
Abstract:
Metallic materials with a Kagome lattice have become a new frontier in Condensed Matter Physics. Their electronic band structure features Dirac points, van Hove singularities (VHS), and flat bands. In this talk, I will present some insightful cases of the Kagome superconductor CsV3Sb5 (CVS), where superconductivity, charge density wave (CDW), and non-trivial topology interplay. Magnetic quantum oscillations measured in fields up to 86 T reveal the fundamental ‘building blocks’ of the reconstructed Fermi surface: ‘hyperbolic hexagon’ and ‘triangular’ pockets in the CDW state of CVS. These pockets, characterized by sharp corners and strong Fermi velocity variations due to proximity to VHS, explain unconventional transport behaviors like non-monotonic magnetoresistance and apparent anomalous Hall effect. This approach extends to anomalous magneto-transport in other metallic systems with singular electronic features. As I conclude the talk, I will briefly discuss anomalous features observed in the temperature dependence of upper critical field Hc2(T) of CVS and propose an explanation based on Fermi surface reconstruction.
Bio: Dr. Ramakanta Chapai is an Assistant Professor of Physics at Norfolk State University. He earned his PhD in Physics from Louisiana State University in 2021 and held postdoctoral appointments at Argonne National Laboratory and Oak Ridge National Laboratory before joining NSU. His research focuses on topological and correlated quantum materials, including kagome metals and superconductors. His work combines single-crystal synthesis, electrical and magnetic measurements, and high-field quantum oscillations to determine how electronic structure, topology, and electronic correlations govern the transport and superconducting properties of these materials.