Researchers at Paul Scherrer Institute (PSI), using muon spin rotation at the Swiss Muon Source (SmS), have discovered that a quantum phenomenon called time-reversal symmetry breaking takes place at the surface of the Kagome superconductor RbV₃Sb₅, occurring at temperatures up to 175 K.

This sets a new record for the temperature at which time-reversal symmetry breaking is observed among Kagome systems.