A two population Ising model on diluted Random Graphs

We consider the Ising model for two interacting groups of spins embedded in an Erd¨os–R´enyi random graph. The critical properties of the system are investigated by means of extensive Monte Carlo simulations. Our results evidence the existence of a phase transition at a value of the inter-groups interaction coupling JC_12 which depends algebraically on the dilution of the graph and on the relative width of the two populations, as explained by means of scaling arguments. We also measure the critical exponents, which are consistent with those of the Curie–Weiss model, hence suggesting a wide robustness of the universality class.