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arXiv · 0902.1450

Unconventional pairing phases in the two-dimensional attractive Hubbard model with population imbalance

Stefan M. A. Rombouts
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Abstract

The ground state phase diagram of the two-dimensional attractive Hubbard model with population imbalance is explored using a mean field ansatz. A linear programming algorithm is used to identify the blocked states, such that the population imbalance can be imposed exactly. This allows to explore regions of the number-projected phase diagram that can not be obtained with the conventional Bogoliubov-de Gennes ansatz. The Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) phase of pairs with non-zero momentum is found to be the ground state over a wide range of parameters, while phase separation occurs only in a limited region at small population imbalance. Through a particle-hole transformation these results can be related to the underdoped repulsive Hubbard model, where the FFLO phase takes the form of a particle-hole condensate that exhibits a spontaneous restoration of spin symmetry.

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Stefan M. A. Rombouts. 2009-02-09. Unconventional pairing phases in the two-dimensional attractive Hubbard model with population imbalance. https://arxiv.org/abs/0902.1450

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