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Title: Cold Attractive Spin Polarized Fermi Lattice Gases and the Doped Positive U Hubbard Model

Abstract

Experiments on polarized fermion gases performed by trapping ultracold atoms in optical lattices allow the study of an attractive Hubbard model for which the strength of the on-site interaction is tuned by means of a Feshbach resonance. Using a well-known particle-hole transformation we discuss how results obtained for this system can be reinterpreted in the context of a doped repulsive Hubbard model. In particular, we show that the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state corresponds to the striped state of the two-dimensional doped positive U Hubbard model. We then use the results of numerical studies of the striped state to relate the periodicity of the FFLO state to the spin polarization. We also comment on the relationship of the dx2y2superconducting phase of the doped 2D repulsive Hubbard model to a d-wave spin density wave state for the attractive case.

Authors:
 [1];  [2]
  1. ORNL
  2. University of California, Santa Barbara
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931029
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 98
Country of Publication:
United States
Language:
English

Citation Formats

Moreo, Adriana, and Scalapino, D. J.. Cold Attractive Spin Polarized Fermi Lattice Gases and the Doped Positive U Hubbard Model. United States: N. p., 2007. Web. doi:10.1103/PhysRevLett.98.216402.
Moreo, Adriana, & Scalapino, D. J.. Cold Attractive Spin Polarized Fermi Lattice Gases and the Doped Positive U Hubbard Model. United States. doi:10.1103/PhysRevLett.98.216402.
Moreo, Adriana, and Scalapino, D. J.. Mon . "Cold Attractive Spin Polarized Fermi Lattice Gases and the Doped Positive U Hubbard Model". United States. doi:10.1103/PhysRevLett.98.216402.
@article{osti_931029,
title = {Cold Attractive Spin Polarized Fermi Lattice Gases and the Doped Positive U Hubbard Model},
author = {Moreo, Adriana and Scalapino, D. J.},
abstractNote = {Experiments on polarized fermion gases performed by trapping ultracold atoms in optical lattices allow the study of an attractive Hubbard model for which the strength of the on-site interaction is tuned by means of a Feshbach resonance. Using a well-known particle-hole transformation we discuss how results obtained for this system can be reinterpreted in the context of a doped repulsive Hubbard model. In particular, we show that the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state corresponds to the striped state of the two-dimensional doped positive U Hubbard model. We then use the results of numerical studies of the striped state to relate the periodicity of the FFLO state to the spin polarization. We also comment on the relationship of the dx2y2superconducting phase of the doped 2D repulsive Hubbard model to a d-wave spin density wave state for the attractive case.},
doi = {10.1103/PhysRevLett.98.216402},
journal = {Physical Review Letters},
number = ,
volume = 98,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Experiments on polarized fermion gases performed by trapping ultracold atoms in optical lattices allow the study of an attractive Hubbard model for which the strength of the on-site interaction is tuned by means of a Feshbach resonance. Using a well-known particle-hole transformation we discuss how results obtained for this system can be reinterpreted in the context of a doped repulsive Hubbard model. In particular, we show that the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state corresponds to the striped state of the two-dimensional doped positive U Hubbard model. We then use the results of numerical studies of the striped state to relate the periodicitymore » of the FFLO state to the spin polarization. We also comment on the relationship of the d{sub x{sup 2}}{sub -y{sup 2}} superconducting phase of the doped 2D repulsive Hubbard model to a d-wave spin density wave state for the attractive case.« less
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  • We consider two-component one-dimensional quantum gases at special imbalanced commensurabilities which lead to the formation of multimer (multiparticle bound-states) as the dominant order parameter. Luttinger liquid theory supports a mode-locking mechanism in which mass (or velocity) asymmetry is identified as the key ingredient to stabilize such states. While the scenario is valid both in the continuum and on a lattice, the effects of umklapp terms relevant for densities commensurate with the lattice spacing are also mentioned. These ideas are illustrated and confronted with the physics of the asymmetric (mass-imbalanced) fermionic Hubbard model with attractive interactions and densities such that amore » trimer phase can be stabilized. Phase diagrams are computed using density-matrix renormalization group techniques, showing the important role of the total density in achieving the latter phase. The effective physics of the trimer gas is studied as well. Last, the effect of a parabolic confinement and the emergence of a crystal phase of trimers are briefly addressed. This model has connections with the physics of imbalanced two-component fermionic gases and Bose-Fermi mixtures as the latter gives a good phenomenological description of the numerics in the strong-coupling regime.« less
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  • We show that the recently discovered {eta}-pairing scheme combined with the Nagaoka-Thouless picture for itinerant ferromagnetism leads to a new type of superconductivity in the attractive-{ital U} Hubbard model in the sector 0{lt}({ital N}{sub {up arrow}}{minus}{ital N}{sub {down arrow}})/({ital N}{sub {up arrow}}+{ital N}{sub {down arrow}}){much lt}1, where {ital N}{sub {up arrow}} and {ital N}{sub {down arrow}} are the occupation numbers of up and down spins. This results holds for all dimensionalities {ital d}{ge}2.