Regensburg 2007 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 30: Poster II
DY 30.3: Poster
Donnerstag, 29. März 2007, 16:00–18:00, Poster D
Quantum Monte Carlo Investigation of Quantum Phase Transitions of Mixed Heisenberg Spin Chains — •Rainer Bischof1, Peter Crompton2, and Wolfhard Janke1 — 1Institut für Theoretische Physik, Universität Leipzig, Germany — 2Center for Theoretical Physics, Massachusetts Institute of Technology, USA
By means of quantum Monte Carlo simulations at low temperatures, the quantum phase transitions in antiferromagnetic Heisenberg spin chains consisting of two different kinds of spin, Sa and Sb, that appear alternatingly in pairs, are investigated for the cases Sa=1/2 and Sb=1, Sa=1/2 and Sb=3/2 as well as Sa=1 and Sb=3/2. Transitions between qualitatively different ground states (quantum phases) are induced by varying the parameter α which is the relative coupling between unlike and like spins. In particular, the so-called twist order parameter as well as spatial and imaginary temporal correlation lengths are measured and analysed. Critical values of α, critical exponents and leading correction terms are extracted by finite-size scaling analysis.