Discovery of a New Phase in Thin Flakes of KV₃Sb₅ under Pressure

Results of magnetotransport measurements are reported on KV₃Sb₅ thin flakes under pressure. The zero-field electrical resistance reveals an additional anomaly emerging under pressure (p), marking a previously unidentified phase boundary T*(p). Together with the established T_CDW(p) and T_c(p), denoting the charge-density-wave transition and a superconducting transition, respectively, the temperature-pressure phase diagram of KV₃Sb₅ features a rich interplay among multiple phases. The Hall coefficient evolves reasonably smoothly when crossing the T* phase boundary compared with the variation when crossing T_CDW, indicating the preservation of the pristine electronic structure. The mobility spectrum analysis provides further insights into distinguishing different phases. Finally, the high-pressure quantum oscillation studies up to 31 T combined with the density functional theory calculations further demonstrate that the new phase does not reconstruct the Fermi surface, confirming that the translational symmetry of the pristine metallic state is preserved.