Properties of Odd Gap Superconductors

TL;DR

This paper explores the theoretical properties of odd-frequency superconductors, focusing on their order parameters, superfluid stiffness, and tunneling characteristics, providing insights into their thermodynamic and transport behaviors.

Contribution

It introduces a model for odd-frequency superconductors using a composite operator and analyzes their superfluid and tunneling properties, advancing understanding of this unconventional pairing state.

Findings

Superfluid stiffness is positive in odd-gap superconductors.

Derived thermodynamic and transport properties of odd-frequency pairing.

Analyzed tunneling behavior with conventional superconductors.

Abstract

We discuss the class of superconductors which have pairing correlations which are odd in frequency, as introduced originally by Berezinskii and more recently by Balatsky and Abrahams. As follows from the equations of motion, a natural definition of the thermodynamic order parameter of the odd-pairing state is the expectation value of a composite operator which couples a Cooper pair to a spin or charge fluctuation. We use a model pairing hamiltonian to describe properties of the odd-pairing composite-operator condensate. We show that the superfluid stiffness is positive, we discuss superconductive tunneling with an ordinary superconductor and we derive other thermodynamic and transport properties.