SμS: Swiss Muon Source

Unconventional superconductors often feature competing orders, small super- fluid density, and nodal electronic pairing. While unusual superconductivity has been proposed in the kagome metals AV3Sb5, key spectroscopic evidence has remained elusive. Here we utilize pressure-tuned and ultra-low temperature muon spin spectroscopy to uncover the unconventional nature of super- conductivity in RbV₃Sb₅ and KV₃Sb₅. At ambient pressure, we observed time- reversal symmetry breaking charge order below T^*₁≃110 K in RbV₃Sb₅ with an additional transition at T^*₂≃50 K. Remarkably ....

Pressure, together with temperature, electric, and magnetic fields, alters the system and allows for the investigation of the fundamental prop- erties of matter. Under applied pressure, the interatomic distances shrink, which modifies the interactions between atoms and may lead to the appearance of new (sometimes exotic) physical properties, such as pressure-induced phase transitions; quantum critical points; new structural, magnetic, and/or superconducting states; and changes of the temperature evolution and symmetry of the order parameters...