Dynamical mean-field study of the Fulde-Ferrell-Larkin-Ovchinnikov phase in the kagome lattice

Abstract

Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) phases are superconducting phases in which Cooper pairs have a nonzero total momentum. Despite experimental efforts to directly observe this state, it has remained elusive, and its existence is supported only by indirect evidence.

In systems featuring a constant dispersion band, also called flat band, unconventional pairing mechanisms could help stabilize exotic superfluid phases. Those systems could thus be good candidates for a direct observation of FFLO phases.

In this work, we study FFLO state in one such system, the kagome lattice, with dynamical mean-field theory (DMFT). We use two different approaches. One is based on including the FF ansatz, an order parameter modulated by a plane wave, in cluster DMFT. The other is a partially real-space DMFT calculation. With both methods, we find a stable FFLO state in the vicinity of the flat band singularity.