Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

High-pressure single-crystal x-ray diffraction experiments reveal that the superconducting kagome metal CsV₃Sb₅ transforms from hexagonal (P6/mmm) to monoclinic (C2/m) symmetry above
10 GPa if nonhydrostatic pressure conditions are created in a diamond anvil cell with silicon oil as pressure-transmitting medium. This is contrary to the behavior of CsV₃Sb₅ under quasi-hydrostatic conditions in neon, with the hexagonal symmetry retained up to at least 20 GPa. Monoclinic distortion leaves the kagome planes almost unchanged but deforms honeycomb nets of the Sb atoms. Using ab initio density-functional calculations, we show that this distortion facilitates the pressure-induced shift of van Hove singularities away from the Fermi level and preserves the overall scenario of the Fermi surface reconstruction caused by the formation of interlayer Sb-Sb bonds.