Order parameter and vortices in the superconducting Q-phase of CeCoIn5

TL;DR

This paper develops a phenomenological theory explaining the coexistence of spin-density wave, pair density wave, and charge density wave orders in CeCoIn5's superconducting Q-phase, revealing how these orders influence vortex structures.

Contribution

It introduces a theoretical framework for the coexisting orders in CeCoIn5 and predicts their effects on vortex core structures and phase behavior.

Findings

SDW order exists only within the Q-phase.

Vortex cores exhibit charge density wave order.

SDW order serves as a probe of the vortex phase.

Abstract

Recently, it has been reported that the low-temperature high-magnetic field phase in CeCoIn5 (Q-phase), has spin-density wave (SDW) order that only exists within this phase. This indicates that the SDW order is the result of the development of pair density wave (PDW) order in the superconducting phase that coexists with d-wave superconductivity. Here we develop a phenomenological theory for these coexisting orders. This provides selection rules for the PDW order and further shows that the detailed structure of this order is highly constrained. We then apply our theory to the the vortex phase. This reveals vortex phases in which the d-wave vortex cores exhibit charge density wave (CDW) order and further reveals that the SDW order provides a unique probe of the vortex phase.