Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 8: Correlated Electrons: Spin Systems and Itinerant Magnets - Frustrated Magnets I
TT 8.13: Vortrag
Montag, 31. März 2014, 12:45–13:00, HSZ 304
Discriminating antiferromagnetic signatures in ultracold fermions by tunable geometric frustration — Chia-Chen Chang1, Richard T. Scalettar1, •Elena V. Gorelik2, and Nils Blümer2 — 1Department of Physics, University of California, Davis, USA — 2Institute of Physics, Johannes Gutenberg University, Mainz, Germany
Recently, it has become possible to tune optical lattices continuously between square and triangular
geometries. We compute thermodynamics and spin correlations in the corresponding Hubbard model using
determinant quantum Monte Carlo and show that the frustration effects induced by the variable hopping
terms can be clearly separated from concomitant bandwidth changes by a proper rescaling of the interaction.
An enhancement of the double occupancy by geometric frustration signals the destruction of nontrivial
antiferromagnetic correlations at weak coupling and entropy s ln(2) (and restores Pomeranchuk
cooling at strong frustration), paving the way to the long-sought experimental detection of
antiferromagnetism in ultracold fermions on optical lattices.
C.-C. Chang, R. T. Scalettar, E. V. Gorelik, and N. Blümer, Phys. Rev. B 88 (2013) 195121.