Study of in‐plane upper critical fields in noncentrosymmetric superconductors CeRhSi₃ and CeIrSi₃ near quantum criticality

Abstract

Upper critical fields H c2 in noncentrosymmetric superconductors CeRhSi 3 and CeIrSi 3 for H ?ẑ are investigated by taking into account both electron correlation effects and higher Landau levels. H c2 ?ẑ is determined mainly by the Pauli depairing effects and almost independent of the applied pressure, in contrast to the H c2 kẑ which is governed by the orbital depairing effects and enhanced near the antiferromagnetic quantum critical point. Such a difference in the mechanism of the pair breaking effects is characteristic of the compounds, and can lead to the anisotropic H c2 observed in the experiments.

Superconductivity and spin–orbit coupling in non-centrosymmetric materials: a review

“…This is compatible with calculations of the spin susceptibility for the permitted triplet state for this structure, 6 which show the absence of Pauli limiting in one direction and an enhanced Pauli limiting field along others. In this scenario, H c2 (T ) would be limited by paramagnetic pair breaking for H ab but would be determined solely by the orbital limiting field for H c, which may be enhanced in proximity to a QCP 70,71 . In this scenario, a magnetization perpendicular to the applied field H ab is predicted in the vortex state, this is discussed in more detail in Section VI E.…”