Time reversal symmetry breaking in superconducting(Pr,La)Os4Sb12superconducting(Pr,La)Os4Sb12 and Pr(Os,Ru)4Sb12Pr(Os,Ru)4Sb12

Zero-field muon spin relaxation (μSR)(μSR) experiments have been carried out in the Pr(Os1-xRux)4Sb12Pr(Os1-xRux)4Sb12 and Pr1-yLayOs4Sb12Pr1-yLayOs4Sb12 alloy systems to investigate the time-reversal symmetry (TRS) breaking found in an earlier ZF-μSRμSR study of the end compound PrOs4Sb12PrOs4Sb12. Our results suggest that Ru doping is considerably more efficient than La doping in suppressing TRS-breaking superconducting pairing in PrOs4Sb12PrOs4Sb12.