Spin-Imbalanced Pairing and Fermi Surface Deformation in Flat Bands

Research output: Contribution to journalArticleScientificpeer-review

Researchers

Research units

Abstract

We study the attractive Hubbard model with spin imbalance on two lattices featuring a flat band: the Lieb and kagome lattices. We present mean-field phase diagrams featuring exotic superfluid phases, similar to the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, whose stability is confirmed by dynamical mean-field theory (DMFT). The nature of the pairing is found to be qualitatively different from the Fermi surface shift responsible for the usual FFLO state. The presence of a flat band allows for changes in the particle momentum distributions at null energy cost. This facilitates formation of nontrivial superfluid phases via multiband Cooper pair formation: the momentum distribution of the spin component in the flat band deforms to mimic the Fermi surface of the other spin component residing in a dispersive band. The Fermi surface of the unpaired particles that are typical for gapless superfluids becomes deformed as well. The results highlight the profound effect of flat dispersions on Fermi surface instabilities, and provide a potential route for observing spin-imbalanced superfluidity and supercondutivity.

Details

Original languageEnglish
Article number214503
Pages (from-to)1-8
JournalPhysical Review B
Volume97
Issue number21
Publication statusPublished - 2018
MoE publication typeA1 Journal article-refereed

    Research areas

  • Condensed Matter - Quantum Gases, Condensed Matter - Superconductivity

Download statistics

No data available

ID: 21096674