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TT: Tiefe Temperaturen

TT 25: Correlated Electrons - Poster Session

TT 25.103: Poster

Mittwoch, 29. März 2006, 14:30–18:30, P1

Thermodynamics of intermediate-spin Heisenberg-chains — •Simon Großjohann and Wolfram Brenig — Institute for Theoretical Physics, Technical University Braunschweig, Germany

We investigate the crossover from quantum to classical behavior in one-dimensional spin-S chains by a complementary analysis of the thermodynamic properties resulting from quantum Monte-Carlo calculations as well as from the large-S limit. Using the stochastic series expansion, results will be given for the thermodynamic limit of chains with spins ranging from S=1/2 to S=5/2 and for temperatures 0.01≤ T/J ≤ 20. We find a tendency of the peak-positions T_m of the quantum and classical uniform susceptibilities, χ_q and χ_c, to converge as S →5/2. However for both, Haldane and non-Haldane systems, substantial quantitative and qualitative differences remain between χ_q and χ_c, regarding the low-temperature behavior even for the larger spin magnitudes. We will compare our results with Bethe-Ansatz calculations and present Padé-approximants for χ_q which improve fit-formulas previously reported in literature.