Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 50: Correlated Electrons: Quantum-Critical Phenomena - Theory

TT 50.2: Vortrag

Dienstag, 1. April 2014, 14:15–14:30, BEY 81

Quantum Monte Carlo Simulations of Trimerized Antiferromagnetic Systems — •Dominik Straßel and Sebastian Eggert — Department of Physics and Research Center Optimas, Technical University Kaiserslautern, 67663 Kaiserslautern, Germany

We study linear clusters of three strongly coupled spins S = 1/2 (trimers), which are connected more weakly in a two dimensional lattice using Stochastic Series Expansion Quantum Monte Carlo simulations of the Heisenberg model in a magnetic field. In general these systems show a magnetization plateau at 1/3 saturation, which is already known from strongly coupled three-leg ladders. Interestingly, the origin of the plateau is very similar to the 1/3 plateau in frustrated lattices (e.g. the triangular lattice) so that the analogous phase transitions can be analyzed using non-frustrated systems, which do not suffer from the infamous minus sign problem. With increasing coupling between the trimers, the plateau vanishes and a critical point can be identified. We also analyze the behavior in the limit of weak inter-trimer coupling.