https://doi.org/10.1140/epjb/e2002-00243-5
Transition to Fulde-Ferrel-Larkin-Ovchinnikov phases near the tricritical point: an analytical study
Laboratoire de Physique Statistique,
École Normale Supérieure (Laboratoire associé au Centre National
de la Recherche Scientifique et aux Universités Paris 6 et Paris 7) ,
24 rue Lhomond, 75231 Paris Cedex 05, France
Corresponding author: a combesco@lps.ens.fr
Received:
20
February
2002
Revised:
4
June
2002
Published online:
13
August
2002
We explore analytically the nature of the transition to the Fulde-Ferrel-Larkin-Ovchinnikov superfluid phases in the vicinity of the tricritical
point, where these phases begin to appear. We make use of an
expansion of the free energy up to an overall sixth order, both in order
parameter amplitude and in wavevector. We first explore the
minimization of this free energy within a subspace, made of arbitrary
superpositions of plane waves with wavevectors of different
orientations but same modulus. We show that the standard second order
FFLO phase transition is unstable and that a first order transition occurs
at higher temperature. Within this subspace we prove that it is favorable
to have a real order parameter and that, among these states, those with
the smallest number of plane waves are preferred. This leads to an order
parameter with a dependence, in
agreement with preceding work. Finally we show that the order
parameter at the transition is only very slightly modified by higher
harmonics contributions when the constraint of working within the
above subspace is released.
PACS: 74.20.Fg – BCS theory and its development / 74.60.Ec – Mixed state, critical fields, and surface sheath
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2002