# Multiple-q current states in a multicomponent superconducting channel

## TL;DR

This paper predicts a new inhomogeneous current state, called multiple-q, in two-component superconducting channels, revealing complex transition behaviors and bistability in supercurrent properties within the Ginzburg-Landau framework.

## Contribution

It introduces the concept of multiple-q states in multicomponent superconductors and analyzes their emergence and properties using Ginzburg-Landau theory.

## Key findings

- Multiple-q states can cause cascade transitions between different current states.
- Presence of multiple-q states leads to bistable supercurrent behavior.
- Characteristic saw-like depairing current dependence indicates multiple-q states.

## Abstract

It is well-established that multicomponent superconductors can host different nonstandard phenomena such as broken-time reversal symmetry (BTRS) states, exotic Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phases, the fractional Josephson effect as well as plenty of topological defects like phase solitons, domain walls and unusual vortex structures. We show that in the case of a two-component superconducting quasi-one-dimensional channel this catalogue can be extended by a novel inhomogeneous current state, which we have termed as a multiple-momenta state or, in short, a multiple-q state, characterized by the coexistence of two different interpenetrating Cooper pair condensates with different total momenta. Within the Ginzburg-Landau formalism for a dirty two-band superconductor with sizable impurity scattering treated in the Born-approximation we reveal that under certain conditions, the occurrence of multiple-q states can induce a cascade of transitions involving switching between them and the homogeneous BTRS (non-BTRS) states and vice versa leading this way to a complex interplay of homogeneous and inhomogeneous current states. We find that hallmarks of such a multiple-q state within a thin wire or channel can be a saw-like dependence of the depairing current and the existence of two distinct stable branches on it (a bistable current state).