Equilibrium properties of disordered spin models with two-scale interactions
Raymond, Jack and Saad, David (2009). Equilibrium properties of disordered spin models with two-scale interactions. Physical review E, 80 (3), 031138.
Official URL: http://pre.aps.org/abstract/PRE/v80/i3/e031138
Methods for understanding classical disordered spin systems with interactions conforming to some idealized graphical structure are well developed. The equilibrium properties of the Sherrington-Kirkpatrick model, which has a densely connected structure, have become well understood. Many features generalize to sparse Erdös- Rényi graph structures above the percolation threshold and to Bethe lattices when appropriate boundary conditions apply. In this paper, we consider spin states subject to a combination of sparse strong interactions with weak dense interactions, which we term a composite model. The equilibrium properties are examined through the replica method, with exact analysis of the high-temperature paramagnetic, spin-glass, and ferromagnetic phases by perturbative schemes. We present results of replica symmetric variational approximations, where perturbative approaches fail at lower temperature. Results demonstrate re-entrant behaviors from spin glass to ferromagnetic phases as temperature is lowered, including transitions from replica symmetry broken to replica symmetric phases. The nature of high-temperature transitions is found to be sensitive to the connectivity profile in the sparse subgraph, with regular connectivity a discontinuous transition from the paramagnetic to ferromagnetic phases is apparent.
|Additional Information:||© 2009 The American Physical Society.|
|Uncontrolled Keywords:||classical disordered spin systems, equilibrium properties, Sherrington-Kirkpatrick model, sparse Erdös-Rényi graph structures, percolation threshold, Bethe lattices, sparse strong interactions, weak dense interactions|
|Divisions:||Schools_of_Study > Engineering & Applied Science|
Schools_of_Study > Engineering & Applied Science > Mathematics (EAS)
|Deposited By:||David Saad|
|Deposited On:||29 Jul 2010 11:14|
|Last Modified:||28 Mar 2013 09:38|
Repository Staff Only: item control page