Collège Doctoral - Doktorandenkollegien

Statistical Physics of Complex Systems

Coventry - Leipzig - Lviv - Nancy

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Publication

Title Quasi-long-range ordering in a finite-size 2D Heisenberg model
Authors Kapikranian O., Berche B. and Holovatch Yu.
Reference J. Phys. A: Math. Theor. 40 (2007) 3741
DOI10.1088/1751-8113/40/14/001
ArXivhep-lat/0611264
Abstract We analyse the low-temperature behaviour of the Heisenberg model on a two-dimensional lattice of finite size. Presence of a residual magnetisation in a finite-size system enables us to use the spin wave approximation, which is known to give reliable results for the XY model at low temperatures T. For the system considered, we find that the spin-spin correlation function decays as 1/r^eta(T) for large separations r bringing about presence of a quasi-long-range ordering. We give analytic estimates for the exponent eta(T) in different regimes and support our findings by Monte Carlo simulations of the model on lattices of different sizes at different temperatures.


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