Anisotropic differential conductance of a mixed parity superconductor/ferromagnet structure

TL;DR

This paper investigates how the differential conductance in a superconductor/ferromagnet structure varies with the pairing symmetry and magnetic field orientation, offering a method to characterize mixed parity superconductors.

Contribution

It introduces a theoretical analysis of anisotropic conductance in mixed parity superconductors attached to ferromagnets, revealing how conductance depends on pairing dominance and magnetic field direction.

Findings

Zero bias conductance depends on the dominant pairing type and magnetic field orientation.

Abrupt change in zero bias conductance at the transition from singlet to triplet dominance.

Method to estimate the s- and p-wave pairing ratio from conductance measurements.

Abstract

We study the electronic transport properties of a superconductor (S) with a mixed s+p-wave pairing attached to a ferromagnetic metal (F) and a normal electrode (N) in an SFN configuration. Using the quasiclassical Green's function method, we compute the differential conductance $\sigma$ of the junction and demonstrate its dependence on the direction of the exchange field relative to the direction of the d-vector of the pair potential. If the p-wave triplet dominates the pairing, the zero bias conductance depends on the relative direction between the triplet d-vector and the exchange field. In contrast, if the s-wave singlet dominates the pairing, the zero bias conductance is isotropic with respect to the field direction. Furthermore, at zero temperature, the zero bias conductance height can only take two values as a function of $r$, the parameter quantifying the relative amount of s- and p-wave pairing, with an abrupt change at $r=1$ when the superconductor goes from a singlet to triplet dominated ground state. Moreover, we show that the relative amount of s- and p-wave pairing, can be estimated from the dependence of the finite bias conductance on the exchange field direction. Our results provide a way to characterize parity-mixed superconductors performing electrical measurements.