Nonlinear magnetic field dependence of the conductance in d-wave NIS tunnel junctions

TL;DR

This paper investigates how the conductance in d-wave superconductor tunnel junctions varies nonlinearly with magnetic field, especially near a surface phase transition, revealing complex dependencies on temperature, doping, and pairing symmetry.

Contribution

It demonstrates that the magnetic field dependence of conductance is nonlinear near a surface phase transition, contrasting with previous linear predictions for small fields.

Findings

Conductance splitting is nonlinear even at low fields.

Surface phase transition influences magnetic field dependence.

Dependence on temperature, doping, and pairing symmetry is significant.

Abstract

The ab-plane NIS-tunnelling conductance in d-wave superconductors shows a zero-bias conductance peak which is predicted to split in a magnetic field. In a pure d-wave superconductor the splitting is linear for fields small on the scale of the thermodynamic critical field. The field dependence is shown to be nonlinear, even at low fields, in the vicinity of a surface phase transition into a local time-reversal symmetry breaking state. The field evolution of the conductance is sensitive to temperature, doping, and the symmetry of the sub-dominant pairing channel.