paper

Universality of the glassy transitions in the two-dimensional +- J Ising model

arXiv:1005.4491 · doi:10.1103/PhysRevE.82.021106

Abstract

We investigate the zero-temperature glassy transitions in the square-lattice +- J Ising model, with bond distribution ; p=1 and p=1/2 correspond to the pure Ising model and to the Ising spin glass with symmetric bimodal distribution, respectively. We present finite-temperature Monte Carlo simulations at p=4/5, which is close to the low-temperature paramagnetic-ferromagnetic transition line located at p=0.89, and at p=1/2. Their comparison provides a strong evidence that the glassy critical behavior that occurs for , , is universal, i.e., independent of p. Moreover, we show that glassy and magnetic modes are not coupled at the multicritical zero-temperature point where the paramagnetic-ferromagnetic transition line and the T=0 glassy transition line meet. On the theoretical side we discuss the validity of finite-size scaling in glassy systems with a zero-temperature transition and a discrete Hamiltonian spectrum. Because of a freezing phenomenon which occurs in a finite volume at sufficiently low temperatures, the standard finite-size scaling limit in terms of does not exist: the renormalization-group invariant quantity should be used instead as basic variable.

9 pages, 17 figs

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