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TT: Fachverband Tiefe Temperaturen
TT 9: CE: (General) Theory 1
TT 9.10: Talk
Monday, March 14, 2011, 16:30–16:45, HSZ 201
New routes to frustration and the suppression of antiferromagnetic signatures — •Nils Blümer and Elena Gorelik — Institut für Physik, Johannes Gutenberg-Universität Mainz, Germany
An established route for studying frustration effects in Hubbard-type models is the addition of frustrating bonds to a bipartite lattice. In particular, one can tune from the square towards the triangular lattice by adding hopping along one diagonal per plaquette with amplitude t′ ∈ [0,t] (for square-lattice hopping t). While this tuning exposes frustration effects, it also changes the coordination (4≤ Z≤ 6), i.e., affects the energy scales and, thereby, all observables in all phases.
We complement the above model with an additional inter-plane hopping tz=√t2−t′2; then t′ ∈ [0,t] tunes between the cubic and the triangular lattice at constant Zeff=6. Our quantum Monte Carlo based dynamical mean-field calculations at half filling (n=1) show that the recently suggested signature [1] of antiferromagnetic (AF) correlations, an enhanced double occupancy at strong coupling, is suppressed (proportional to t′2) even before the AF order breaks down; in contrast, nonmagnetic phases are unaffected. This confirms our strong-coupling picture [1] quantitatively and should be useful for cold-atom experiments.
E. V. Gorelik, I. Titvinidze, W. Hofstetter, M. Snoek, and N. Blümer, Phys. Rev. Lett. 105, 065301 (2010).