Zero-field finite-momentum and field-induced superconductivity in altermagnets

TL;DR

This paper investigates how spin-singlet superconductivity can occur in altermagnets, revealing that finite-momentum pairing and field-induced superconductivity are possible even without net magnetization, especially with d-wave symmetry.

Contribution

It demonstrates the emergence of finite-momentum superconductivity in altermagnets and maps the phase diagram including high-field superconductivity, a novel insight into altermagnet behavior.

Findings

Finite-momentum superconductivity can occur in altermagnets without net magnetization.

Superconductivity appears at high magnetic fields from a normal state.

Rich phase diagram with field-induced superconducting phases.

Abstract

We explore the possibilities for spin-singlet superconductivity in newly discovered altermagnets. Investigating $d$-wave altermagnets, we show that finite-momentum superconductivity can easily emerge in altermagnets even though they have no net magnetization, when the superconducting order parameter also has $d$-wave symmetry with nodes coinciding with the altermagnet nodes. Additionally, we find a rich phase diagram when both altermagnetism and an external magnetic field are considered, including superconductivity appearing at high magnetic fields from a parent zero-field normal state.