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TT: Fachverband Tiefe Temperaturen
TT 9: CE: (General) Theory 1
TT 9.9: Vortrag
Montag, 14. März 2011, 16:15–16:30, HSZ 201
Dimensional aspects of antiferromagnetism: dynamical mean-field theory versus direct quantum Monte Carlo — •Elena V. Gorelik1, Theresa Paiva2, Richard Scalettar3, and Nils Blümer1 — 1Institute of Physics, Johannes Gutenberg University, Mainz, Germany — 2Instituto de Fisica, Universidade Federal do Rio de Janeiro, Brazil — 3Department of Physics, UC Davis, USA
Although the dynamical mean-field theory (DMFT) is well established for strongly correlated fermions, it is clear that nonlocal correlations will modify all DMFT results. Thus, the recently revealed [1] antiferromagnetic (AF) signatures in the double occupancy D of fermions on a cubic lattice could shift to lower T or the DMFT scenario might even break down. The situation should be worse in 2 dimensions, for which the Mermin-Wagner theorem excludes AF order at T>0.
However, our DMFT predictions for D(T) in the square-lattice agree with direct quantum Monte Carlo (QMC) results [2] within 10%. In 3 dimensions, we find nearly exact agreement between DMFT and QMC both at large T and for T≲ TNDMFT. The primary effect of nonlocal correlations is a smoothing of the DMFT curves at T≳ TNDMFT.
Somewhat surprisingly, TNDMFT is much more relevant for the AF signatures in D(T) than the true TN.
Thus, magnetism is more local in many respects than previously assumed, and real-space DMFT is well-suited
for addressing inhomogeneous 3-dimensional systems.
E. V. Gorelik, I. Titvinidze, W. Hofstetter, M. Snoek, and N. Blümer, Phys. Rev. Lett. 105, 065301 (2010).
Th. Paiva, R. Scalettar, M. Randeria, and N. Trivedi, Phys. Rev. Lett. 104, 066406 (2010).