Tunneling and Josephson effects in odd-frequency superconductor junctions: A study on multi-channel Kondo chain

TL;DR

This paper explores the unique tunneling and Josephson effects in odd-frequency superconductor junctions, using a two-channel Kondo lattice model to reveal distinctive conductance and pairing symmetries.

Contribution

It introduces a mean-field Hamiltonian approach to analyze OF superconductor junctions, highlighting the role of normal reflection and symmetry in their unique properties.

Findings

Normal reflection is always present in OF superconductor junctions.

Conductance varies with interface potential, differing from conventional superconductors.

Symmetry considerations explain the Meissner response in bulk OF superconductors.

Abstract

Junction systems of odd-frequency (OF) superconductors are investigated based on a mean-field Hamiltonian formalism. One-dimensional two-channel Kondo lattice (TCKL) is taken as a concrete example of OF superconductors. Properties of normal and Andreev reflections are examined in a normal metal/superconductor junction. Unlike conventional superconductors, normal reflection is always present due to the normal self energy that necessarily appears in the present OF pairing state. The conductance reflects the difference between repulsive and attractive potentials located at the interface, which is in contrast with the preexisting superconducting junctions. Josephson junction is also constructed by connecting TCKL with the other types of superconductors. The results can be understood from symmetry of the induced Cooper pairs at the edge in the presence of spin/orbital symmetry breaking. It has also been demonstrated that the symmetry argument for Cooper pairs is useful in explaining Meissner response in bulk.