Phase Slips and Interfaces in D-Wave Superconductors

TL;DR

This paper models a (100) interface between two d-wave superconductors, analyzing how phase differences and barriers affect local order parameters, density of states, and Josephson current, revealing resonant sub-gap states linked to phase slips.

Contribution

It introduces a detailed Bogoliubov de Gennes model for d-wave superconductor interfaces, highlighting the impact of phase slips and barriers on local order parameters and electronic properties.

Findings

Resonant sub-gap states occur only with phase slip.

Local s-wave and p-wave components are sensitive to barrier and phase slip.

P-wave order parameter temperature dependence follows bulk Tc.

Abstract

We consider a model (100) interface between two d-wave superconductors. By solving the Bogoliubov de Gennes equation on a tight binding lattice, we study the properties of the interface as a function of the interface barrier. We contrast the two scenarios: (i) an order parameter phase difference of $\theta=0$ across the interface, and (ii) a phase slip of $\theta=\pi$ across the interface. We find resonant sub-gap structure in the density of states only when there is a phase slip present. We show that the local s-wave and ``p-wave like'' order parameter components are strongly influenced by the barrier profile and by the phase slip. The temperature dependence of the local p-wave order parameter follows the underlying bulk $T_c$ for p-wave superconductivity implying that this could be measured by a suitable tunneling experiment. We also calculate the Josephson critical current as a function of the strength of the insulating barrier at the interface.