Superconductors of mixed order parameter symmetry in a Zeeman magnetic field

TL;DR

This paper investigates how a Zeeman magnetic field influences superconductors with mixed order parameters, revealing that the field can suppress minor components or induce different responses depending on the phase, which contrasts with effects from other field orientations.

Contribution

It provides new insights into the behavior of mixed-symmetry superconductors under Zeeman fields, highlighting the dependence on the phase of the minor component and contrasting effects of magnetic field orientation.

Findings

Weak magnetic fields suppress minor order parameter components in certain orientations.

Response of superconductors varies with the phase of the minor component.

Magnetic field orientation significantly affects the superconducting phase behavior.

Abstract

We study the effect of Zeeman magnetic field in the superconducting phase with two component order parameter scenario, such as, $d_{x^2-y^2} + e^{i\theta}{\alpha}$, where $\alpha = d_{xy}, s$. This scenario is equivalent to applying magnetic field parrllel to Cu-O planes. In a weak magnetic field, which does not cause much change to the predominant d-wave, supresses the minor $\alpha$ component leading to pure d-wave phase. This observation is in contrary to the effect of magnetic field applied in the c-direction to the Cu-O planes which is believed to induce a minor component $\alpha$ to d-wave superconductors. We also show that the response of such superconductors to a weak Zeeman magnetic field can be quite different depending on the phase $\theta$ of the minor component ($\alpha$).