Magnetic structure of an imbalanced Fermi gas in an optical lattice

Journal Article · Fri Jan 15 00:00:00 EST 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.81.013616· OSTI ID:21388778

Wunsch, B; Fritz, L; Zinner, N T; Demler, E ^[1]; Manousakis, E ^[2]

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1. Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)
2. Department of Physics and MARTECH, Florida State University, Tallahassee, FL 32306-4350 (United States)

We analyze the repulsive fermionic Hubbard model on square and cubic lattices with spin imbalance and in the presence of a parabolic confinement. We analyze the magnetic structure as a function of the repulsive interaction strength and polarization. In the first part of the article, we perform unrestricted Hartree-Fock calculations for the two-dimensional (2D) case and find that above a critical interaction strength U{sub c} the system turns ferromagnetic at the edge of the trap, which is in agreement with the ferromagnetic Stoner instability of a homogeneous system away from half-filling. For U<U{sub c}, we find a canted antiferromagnetic structure in the Mott region in the center and a partially polarized compressible edge. The antiferromagnetic order in the Mott plateau is perpendicular to the direction of the imbalance. In this regime, the same qualitative behavior is expected for 2D and three-dimensional (3D) systems. In the second part of the article, we give a general discussion of magnetic structures above U{sub c}. We argue that spin conservation leads to nontrivial textures, both in the ferromagnetic polarization at the edge and for the Neel order in the Mott plateau. We discuss differences in magnetic structures for 2D and 3D cases.

• OSTI ID: 21388778
• Journal Information: Physical Review. A, Vol. 81, Issue 1; Other Information: DOI: 10.1103/PhysRevA.81.013616; (c) 2010 The American Physical Society; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
ANTIFERROMAGNETISM
CONFINEMENT
CUBIC LATTICES
FERMI GAS
FERMIONS
HARTREE-FOCK METHOD
HUBBARD MODEL
INTERACTIONS
POLARIZATION
SPIN
THREE-DIMENSIONAL CALCULATIONS
TWO-DIMENSIONAL CALCULATIONS
ANGULAR MOMENTUM
APPROXIMATIONS
CALCULATION METHODS
CRYSTAL LATTICES
CRYSTAL MODELS
CRYSTAL STRUCTURE
MAGNETISM
MATHEMATICAL MODELS
PARTICLE PROPERTIES