Unconventional superconductivity in Cr-based compound Pr3Cr10−xN11.

We report results of specific heat and muon spin relaxation (μSR) measurements on a polycrystalline sample of Pr₃Cr_10−xN₁₁, which shows superconducting state below T_c = 5.25 K, a large upper critical field H_c2 ~ 20 T and a residual Sommerfeld coefficient γ₀. The field dependence of γ₀(H) resembles γ of the U-based superconductors UTe₂ and URhGe at low temperatures. The temperature-dependent superfluid density measured by transverse-field μSR experiments is consistent with a p-wave pairing symmetry. ZF-μSR experiment suggests a time-reversal symmetry broken superconducting transition, and temperature-independent spin fluctuations at low temperatures are revealed by LF-μSR experiments. These results indicate that Pr₃Cr_10−xN₁₁ is a candidate of p-wave superconductor which breaks time-reversal symmetry. [ABSTRACT FROM AUTHOR]