Spin-fluctuation-mediated pairing in the heavy fermion superconductors without inversion symmetry CeRhSi3 and CeIrSi3 Original Research Article

We study the pairing symmetry of the noncentrosymmetric heavy fermion superconductors CeRhSi3 and CeIrSi3 under pressures, which are both antiferromagnets at ambient pressure. We solve the Eliashberg equation by means of the random phase approximation and find that the mixing state of extended s -wave and p -wave rather than the d+fd+f wave state could be realized by enhanced antiferromagnetic spin fluctuations. The gap function has line nodes on the Fermi surface. We also examine the NMR relaxation rate in the superconducting state and find that 1/(T1T)1/(T1T) exhibits no coherence peak and behaves as 1/(T1T)∝T21/(T1T)∝T2.