VIOLATION OF TIME-REVERSAL SYMMETRY IN AN UNCONVENTIONAL SUPERCONDUCTOR

We analyze theoretically a domain wall structure associated with time reversal symmetry breaking in an unconventional superconducting pairing function, The doubly degenerate states necessarily form domain wall boundary where two kinds of randomly created degenerate states meet in a sample, giving rise to spatially varied magnetic field across it and associated screening current along it. This non-uniform field yields the anomalous increase of the muon spin relaxation time recently observed in a heavy Fermion material UPt3 below the second transition temperature.