Impurity-induced broadening of the transition to a Fulde-Ferrell-Larkin-Ovchinnikov phase

TL;DR

This paper investigates how impurities cause broadening of the phase transition to a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state in CeCoIn$_5$, supporting the identification of the high field low temperature phase as a longitudinal FFLO vortex state.

Contribution

It provides a theoretical explanation for impurity-induced broadening of the FFLO transition, linking disorder effects to the softness of FFLO nodal planes.

Findings

Impurities cause significant broadening of the FFLO transition.

The broadening is due to the softness of FFLO nodal planes.

Results support the FFLO vortex state interpretation of the HFLT phase.

Abstract

Recent study on doping effects in the heavy fermion superconductor CeCoIn$_5$ has shown that a small amount of doping induces unexpectedly large broadening of the second order transition into the high field and low temperature (HFLT) phase of this material. Motivated by this observation, effects of quenched disorder on the second order transition into a longitudinal Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state are examined. The observed large broadening of the transition is naturally explained as a consequence of softness of each FFLO nodal plane. The present results strongly support the scenario identifying the HFLT phase of CeCoIn$_5$ with a longitudinal FFLO vortex state.