Time-reversal symmetry-breaking superconductivity in heavy-fermion PrOs4Sb12 detected by muon-spin relaxation

Phys Rev Lett. 2003 Aug 8;91(6):067003. doi: 10.1103/PhysRevLett.91.067003. Epub 2003 Aug 6.


We report on muon-spin relaxation measurements of the 4f(2)-based heavy-fermion superconductor filled-skutterudite Pr(Os4Sb12. The results reveal the spontaneous appearance of static internal magnetic fields below the superconducting transition temperature, providing unambiguous evidence for the breaking of time-reversal symmetry in the superconducting state. A discussion is made on which of the spin or orbital component of Cooper pairs carries a nonzero momentum.