QMC simulations of Heisenberg ferromagnet

We use the Quantum Monte Carlo Stochastic Series Expansion (SSE) algorithm to investigate the properties of the one-dimensional Heisenberg ferromagnet. We consider the model for two spin values s = 1 2 and s = 1 and study the dependence of the specific heat, magnetisation, magnetic susceptibility and correlation functions on temperature and magnetic field. Obtained results are compared to those derived by analytical methods (Bethe ansatz, Green’s function, Random Phase Approximation). In particular, the surprising prediction of a double-peak structure in the specific heat at low temperatures and small magnetic fields can be confirmed.