Chiral superconductors are unconventional superconducting materials with distinctive topological properties, in which time-reversal symmetry is broken. Two of the first materials to be identified as chiral superconductors are UPt3 and Sr2RuO4. So far, experimental evidence for broken time-reversal symmetry in both these materials was based primarily on surface measurements collected at a magnetic field equal to zero.
Source:
https://phys.org/news/2020-03-evidence-broken-time-reversal-symmetry-topological.html