Spin fluctuations and superconductivity in noncentrosymmetric heavy fermion systems CeRhSi3 and CeIrSi3

Abstract

We study the normal and the superconducting properties in noncentrosymmetric heavy fermion superconductors CeRhSi3 and CeIrSi3. For the normal state, we show that experimentally observed linear temperature dependence of the resistivity is understood through the antiferromagnetic spin fluctuations near the quantum critical point (QCP) in three dimensions. For the superconducting state, we derive a general formula to calculate the upper critical field Hc2, with which we can treat the Pauli and the orbital depairing effect on an equal footing. The strong coupling effect for general electronic structures is also taken into account. We show that the experimentally observed features in Hc2∥ẑ, the huge value up to 30 (T), the downward curvatures, and the strong pressure dependence, are naturally understood as an interplay of the Rashba spin-orbit interaction due to the lack of inversion symmetry and the spin fluctuations near the QCP. The large anisotropy between Hc2∥ẑ and Hc2⊥ẑ is explained in terms of the spin-orbit interaction. Furthermore, a possible realization of the Fulde-Ferrell-Larkin-Ovchinnikov state for H⊥ẑ is studied. We also examine effects of spin-flip scattering processes in the pairing interaction and those of the applied magnetic field on the spin fluctuations. We find that the above-mentioned results are robust against these effects. The consistency of our results strongly supports the scenario that the superconductivity in CeRhSi3 and CeIrSi3 is mediated by the spin fluctuations near the QCP.

Source-reported materials — not catalogue approval

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