Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 34: Correlated Electrons: Spin Systems and Itinerant Magnets
TT 34.2: Vortrag
Freitag, 31. März 2006, 10:30–10:45, HSZ 301
Phase diagram of the two-dimensional quantum Heisenberg antiferromagnet with an easy-axis anisotropy — •Martin Holtschneider1, Stefan Wessel2, and Walter Selke1 — 1Institut für Theoretische Physik, RWTH Aachen — 2Institut für Theoretische Physik, Universität Stuttgart
The square lattice spin-1/2 Heisenberg antiferromagnet with an easy-axis anisotropy is studied in an external magnetic field, using Quantum Monte Carlo simulations based on the stochastic series expansions with a directed loop update. The model displays long range ordered antiferromagnetic, algebraically ordered spin-flop, and paramagnetic phases. The low-temperature phase diagram is determined by studying both thermodynamic quantities such as the (staggered) suszeptibility and the staggered magnetization as well as histograms of e.g. the order parameter distribution. The numerical results are compared to previous findings on this model (being equivalent to a hard core boson Hubbard model), in particular G. Schmid et al., Phys. Rev. Lett. 88, 167208 (2002), and the results on the corresponding classical model in M. Holtschneider et al., Phys. Rev. B 72, 064443 (2005).