Sala 422 15:15 

dr Oleg Derzhko, Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine

Low-temperature thermodynamics of some frustrated quantum Heisenberg antiferromagnets

Based on exact diagonalization data for finite quantum Heisenberg antiferromagnets on some frustrated lattices and analytical arguments we map low-energy degrees of freedom of the spin models in a magnetic field onto classical lattice-gas models. Using transfer matrix calculations and classical Monte Carlo simulations we give a quantitative description of low-temperature thermodynamics of the quantum spin models. We extend the discussion to the case when the chirality degrees of freedom come into play. The elaborated scheme may be applied to the repulsive Hubbard model too. Further details can be found in: arXiv.1009.3828, arXiv.1103.5124, and arXiv.1108.5453.