Mixed-symmetry superconductivity and the energy gap

TL;DR

This paper explores how mixed singlet-triplet superconducting phases can form below the critical temperature in a generic model, affecting the energy gap structure and requiring comprehensive temperature-dependent measurements for full understanding.

Contribution

It demonstrates the emergence of mixed-symmetry superconducting phases in a generic model and analyzes their impact on the energy gap and density of states across temperatures.

Findings

Mixed-symmetry phases can arise below T_c.

Density of states varies significantly with temperature.

Full symmetry characterization requires measurements over the entire temperature range.

Abstract

The symmetry of the superconducting order parameter, or simply the ``gap'', provides certain constraints on the actual mechanism that gives rise to pairing and ultimately to superconductivity. In this work we show how superconducting phases with mixed singlet-triplet symmetries can arise below $T_c$ for a generic tight-binding model. We first examine the 1D case to better illustrate the prevalence of symmetry-breaking transitions below $T_c$, and then the more realistic 2D case. In both cases we illustrate the implication for spectroscopic investigations of the energy gap by calculating the density of states for different temperatures below $T_c$. We find that the structure of the density of states near $T_c$ can vary dramatically from its form near $T=0$. A complete picture of the superconducting symmetry can only be attained if measurements are made over the entire temperature range.