Properties of spin-triplet, even-parity superconductors

TL;DR

This paper investigates the theoretical properties of spin-triplet, even-parity superconductors in disordered two-dimensional systems, revealing a phase transition to a superconducting state with characteristic electromagnetic responses.

Contribution

It provides a detailed theoretical analysis of the phase transition and properties of spin-triplet, even-parity superconductors in disordered systems, including mean-field and fluctuation effects.

Findings

Disorder induces an instability leading to superconductivity.

The transition is continuous with a diverging length scale.

The superconducting phase exhibits a Meissner effect.

Abstract

The physical consequences of the spin-triplet, even-parity pairing that has been predicted to exist in disordered two-dimensional electron systems are considered in detail. We show that the presence of an attractive interaction in the particle-particle spin-triplet channel leads to an instability of the normal metal that competes with the localizing effects of the disorder. The instability is characterized by a diverging length scale, and has all of the characteristics of a continuous phase transition. The transition and the properties of the ordered phase are studied in mean-field theory, and by taking into account Gaussian fluctuations. We find that the ordered phase is indeed a superconductor with an ordinary Meissner effect and a free energy that is lower than that of the normal metal. Various technical points that have given rise to confusion in connection with this and other manifestations of odd-gap superconductivity are also discussed.