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arXiv:1307.1639 · Physical Review A

Unconventional superfluidity in quasi-one-dimensional systems

Shun Uchino, Akiyuki Tokuno, Thierry Giamarchi

Published Feb 18, 2014• 3 citations
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Abstract

We show that an unconventional superfluid triggered by spin-orbit coupling is realized for repulsively interacting quasi-one-dimensional fermions. A competition between spin-singlet and -triplet pairings occurs due to the breaking of inversion symmetry. We show that both superfluid correlations decay algebraically with the same exponent except for special coupling constants for which a dominant superfluid is controlled by the spin-orbit coupling. We also discuss a possible experiment to observe such phases with cold atoms.

DOI
10.1103/physreva.89.023623

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We show that an unconventional superfluid triggered by spin-orbit coupling is realized for repulsively interacting quasi-one-dimensional fermions. A competition between spin-singlet and -triplet pairings occurs due to the breaking of inversion symmetry. We show that both superfluid correlations decay algebraically with the same exponent except for special coupling constants for which a dominant superfluid is controlled by the spin-orbit coupling. We also discuss a possible experiment to observe such phases with cold atoms.
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We describe the emergence of color superfluidity in ultra-cold fermions induced by color-orbit and color-flip fields that transform a conventional singlet-pairing s-wave system into an unconventional non-s-wave superfluid with quintuplet pairing. We show that the tuning of interactions, color-orbit and color-flip fields transforms a momentum-independent scalar order parameter into an explicitly momentum-dependent tensor order parameter. We classify all unconventional superfluid phases in terms of the {\it loci} of zeros of their quasi-particle excitation spectrum in momentum space and we identify several Lifshitz-type topological transitions. Furthermore, when boundaries between phases are crossed, non-analyticities in the compressibility arise. We find a quintuple point, which is also pentacritical, where four gapless superfluid phases converge into a fully gapped superfluid phase.