Odd-frequency pairing and Josephson effect at superconducting interfaces

TL;DR

This paper reveals that superconducting interfaces induce odd-frequency pairing components, which can lead to Josephson effects between odd- and even-frequency superconductors, and proposes a method to detect such states.

Contribution

It demonstrates the general induction of odd-frequency pairing at interfaces and suggests a way to experimentally probe odd-frequency superconductivity.

Findings

Induced odd-frequency pairing is enhanced by midgap Andreev resonant states.

Josephson effect can occur between odd- and even-frequency superconductors.

A proposed method to detect odd-frequency superconductors.

Abstract

We demonstrate that, quite generally, the spin-singlet even-parity (spin-triplet odd-parity) pair potential in a superconductor induces the odd-frequency pairing component with spin-singlet odd-parity (spin-triplet even-parity) near interfaces. The magnitude of the induced odd-frequency component is enhanced in the presence of the midgap Andreev resonant state due to the sign change of the anisotropic pair potential at the interface. The Josephson effect should therefore occur between odd- and even-frequency superconductors, contrary to the standard wisdom. A method to probe the odd-frequency superconductors is proposed.