SEMINAR 2025

Abstract

Vanadium-based kagome superconductors AV3Sb5 (A=K, Rb, Cs) feature a rich interplay between superconductivity and charge ordering. These phases can be effectively disentangled by applying hydrostatic pressure. I will discuss our approach to probe the normal state and the superconductivity of AV3Sb5 by transport current under pressure. Magnetoresistance up to ~31 T reveals quantum oscillations, allowing the analysis of the Fermi surface. In particularly, large frequencies >8000 T emerge when the charge order is suppressed by pressure, revealing the pristine Fermi surface before the reconstruction [1,2]. In the superconducting state, our self-field critical current measurements in CsV3Sb5 exhibit a temperature dependence that can be understood with a nodeless superconducting gap, which is consistent with our finding that Tc is insensitive to sample purity [3]. Finally, the self-field critical current at the zero-temperature limit shows a drastic enhancement near the border of the charge order where Tc is also enhanced, hinting at the role of charge fluctuations on superconductivity [4].

References:
[1] W. Zhang et al., PNAS (2024)
[2] Z. Wang et al., Advanced Science (2025)
[3] W. Zhang et al., Nano Lett. (2023)
[4] W. Wang et al., Advanced Science (2024)