Session A45: Focus Session: Exploring Quantum Phases in Cold Atom Systems
8:00 AM–11:00 AM, Monday, March 21, 2011
Room: A310
Sponsoring Unit:
DAMOP
Chair: Congjun Wu, University of California, San Diego
Abstract ID: BAPS.2011.MAR.A45.11
Abstract: A45.00011 : Unbalanced fermion mixtures on an optical lattice
10:24 AM–10:36 AM
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Abstract 
Authors:
Chuntai Shi
(University of California Riverside)
Tun Wang
(IQOQI-University of Innsbruck, Austria)
Shan-Wen Tsai
(University of California Riverside)
We study a two component fermion mixture on a square lattice. We describe such system by a Hubbard model wherein there is only on-site interaction between fermions of different species. Such a model can be realized by loading ultra cold fermions onto an optical lattice and by tuning the interaction strength via Feshbach resonance. We investigate the phase diagram of this system near half filling using the functional renormalization group approach for interacting fermions[1]. We focus on the interesting case where one species is at half filling so that their Fermi surface is nested while the other species is slightly doped so that their Fermi surface is not perfectly nested. We study both the cases with repulsive interaction and the cases with attractive interaction. For the attractive interaction, triplet pairing BCS instability among majority species compete with the singlet s-wave inter-species BCS pairing instability when the populations of two species are different. For the repulsive interaction, fermions with equal population are known to display d-wave singlet BCS pairing when both species are slightly doped away from half filling. When only one species of fermions is doped away from half filling, such d-wave instability is weakened while triplet pairing among majority species becomes possible. \\[0pt] [1]. R. Shankar, Rev. Mod. Phys. 66, 129 (1994).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.MAR.A45.11