Colossal Enhancement Of Upper Critical Fields In Noncentrosymmetric Heavy Fermion Superconductors Near Quantum Criticality: Cerhsi_3 And Ceirsi_3

摘要

Strong-coupling effects on the upper critical fields H_(c2) along the c axis in the noncentrosymmetric heavy fermion superconductors near quantum criticality CeRhSi_3 and CeIrSi_3 are examined. For sufficiently large spin-orbit interactions due to the lack of inversion symmetry, H_(c2) is mainly determined by the orbital depairing effects. From microscopic calculations taking into account the strong spin fluctuations, we show that H_(c2) is extremely enhanced as the system approaches the quantum critical point, resulting in H_(c2) ～ 30 T even in the case of a low transition temperature T_c(H = 0) ～ 1 K, which explains well the huge H_(c2) observed in the recent experiments.