Large upper critical field in non-centrosymmetric superconductor Y2C3

Abstract We determine the upper critical field μ 0 H c 2 ( T c ) of non-centrosymmetric superconductor Y 2 C 3 using two distinct methods: the bulk magnetization M ( T ) and the tunnel-diode oscillator (TDO) based impedance measurements. It is found that the upper critical field reaches a value of 30 T at zero temperature which is above the weak-coupling Pauli paramagnetic limit. We argue that the observation of such a large μ 0 H c 2 ( 0 ) in Y 2 C 3 could be attributed to the admixture of spin-singlet and spin-triplet pairing states as a result of broken inversion symmetry.