Time reversal symmetry breaking superconductivity

TL;DR

This paper investigates how time reversal symmetry breaking in superconductors with mixed order parameters leads to distinct thermal, angular, and transport behaviors, influenced by minor components and electron correlations.

Contribution

It demonstrates the impact of minor order parameter components and phase on the properties of time reversal symmetry breaking superconductors, highlighting the role of orthorhombicity and electron correlations.

Findings

Different behaviors depending on minor components and phase at low temperatures.

Orthorhombicity enhances mixed phase stability.

Electron correlations favor pure d_{x^2-y^2} symmetry near optimal doping.

Abstract

We study time reversal symmetry breaking superconductivity with $\Delta_k = \Delta_{x^2-y^2} (k) +e^{i\theta} \Delta_{\alpha}$ ($\alpha = s$ or $d_{xy}$) symmetries. It is shown that the behavior of such superconductors could be {\em qualitatively} different depending on the minor components ($\alpha$) and its phase at lower temperatures. It is argued that such {\em qualitatively different} behaviors in thermal as well as in angular dependencies could be a {\em source} of consequences in transport and Josephson physics. Orthorhombicity is found to be a strong mechanism for mixed phase (in case of $\alpha = s$). We show that due to electron correlation the order parameter is more like a pure $d_{x^2-y^2}$ symmetry near optimum doping.