Ginzburg-Landau theory of noncentrosymmetric superconductors

Abstract

The data of temperature-dependent superfluid density ns(T) in Li2Pd3B and Li2Pt3B [Yuan et al., Phys. Rev. Lett. 97, 017006 (2006)] show that a sudden change of the slope of ns(T) occurs at a temperature slightly lower than the critical temperature. Motivated by this observation, we microscopically derive the Ginzburg-Landau (GL) equations for noncentrosymmetric superconductors with Rashba-type spin-orbit interaction. Cooper pairing is assumed to occur between electrons which are only in the same spin-split band, and pair scattering is allowed to occur between two spin-split bands. The GL theory of such a system predicts two transition temperatures, the higher of which is the conventional critical temperature Tc while the lower one T* corresponds to the crossover from a mixed singlet-triplet phase at lower temperatures to only a spin-singlet or spin-triplet (depending on the sign of the interband scattering potential) phase at higher temperatures. As a consequence, ns(T) shows a kink at this crossover temperature. We attribute the temperature at which the sudden change of slope occurs in the observed ns(T) to the temperature T*. This may also be associated with the observed kink in the penetration depth data of CePt3Si. We have also estimated the critical field near the critical temperature.

Source-reported materials — not catalogue approval

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