Pressure-driven electronic instabilities in kagome superconductors

Together with a team of researchers from KIT, we have investigated the pressure-dependent charge-density-wave (CDW) order in the layered kagome superconductor CsV₃Sb₅, part of an exciting new class of quantum materials. The findings, recently published in Physical Review Letters, reveal that the pressure-dependent CDW order has a direct impact on superconductivity.

Our study shows that at low temperatures and around p ∼ 0.7 GPa, the electronic superlattice undergoes a transition from the familiar 2 × 2 pattern to a novel modulation with wave vector q = (0, 3/8, 1/2). This structural change aligns with a peak in the superconducting transition temperature T_c. Similarly, the suppression of the (0, 3/8, 1/2) modulation at 2 GPa also correlates with a peak in T_c, suggesting that fluctuations in the electronic superlattice may play a role in stabilizing the superconducting state.

These findings challenge the standard models of CDW order, which predict minimal pressure dependence, and cast doubt on more conventional Peierls-like nesting mechanisms involving Van Hove singularities. Instead, our results point to a far more unconventional mechanism underlying the electronic order in these kagome superconductors. That's exiting and there still is a lot to be done and understood!

Original publication:
Pressure-Dependent Electronic Superlattice in the Kagome Superconductor CsV₃⁢Sb₅,
F. Stier, A.-A. Haghighirad, G. Garbarino, S. Mishra, N. Stilkerich, D. Chen, C. Shekhar,
T. Lacmann, C. Felser, T. Ritschel, J. Geck, M. Le Tacon, Phys. Rev. Lett. 133, 236503 (2024)