Title
Controlling the pair momentum of the Fulde-Ferrell-Larkin-Ovchinnikov state in a three-dimensional Fermi gas through a one-dimensional periodic potential Controlling the pair momentum of the Fulde-Ferrell-Larkin-Ovchinnikov state in a three-dimensional Fermi gas through a one-dimensional periodic potential
Author
Faculty/Department
Faculty of Sciences. Physics
Publication type
article
Publication
Lancaster, Pa ,
Subject
Physics
Source (journal)
Physical review : A : atomic, molecular and optical physics. - Lancaster, Pa, 1990 - 2015
Volume/pages
84(2011) :4 , p. 043623,1-043623,8
ISSN
1094-1622
1050-2947
Article Reference
043623
Carrier
E-only publicatie
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
The question whether a spin-imbalanced Fermi gas can accommodate the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state has been the subject of intense study. This state, in which Cooper pairs obtain a nonzero momentum, has hitherto eluded experimental observation. Recently, we demonstrated that the FFLO state can be stabilized in a 3D Fermi gas, by adding a 1D periodic potential. Until now it was assumed that the FFLO wave vector always lies parallel to this periodic potential (FFLO-P). In this contribution we show that, surprisingly, the FFLO wave vector can also lie skewed with respect to the potential (FFLO-S). Starting from the partition sum, the saddle-point free energy of the system is derived within the path-integral formalism. Minimizing this free energy allows us to study the different competing ground states of the system. To qualitatively understand the underlying pairing mechanism, we visualize the Fermi surfaces of the spin-up and spin-down particles. From this visualization, we find that tilting the FFLO wave vector with respect to the direction of the periodic potential can result in a larger overlap between the pairing bands of both spin species. This skewed FFLO state can provide an additional experimental signature for observing FFLO superfluidity in a 3D Fermi gas.
Full text (open access)
https://repository.uantwerpen.be/docman/irua/cd0728/b021dbd4.pdf
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