2010/04/30 by Thierry Dauxois, Pierre de Buyl, Leonardo Lori +1 · 2 citations
Physics and Astronomy · #Opinion Dynamics and Social Influence #Statistical Mechanics and Entropy #Theoretical and Computational Physics #cond-mat.stat-mech
paper · pdf · doi:10.1088/1742-5468/2010/06/p06015
published as J. Stat. Mech. (2010) P06015
arxiv created 2010/05/25 · openalex publication_date 2010/06/15 · arxiv updated 2010/06/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We study the phase diagram of two different Hamiltonians with competing local, nearest-neighbour, and mean-field couplings. The first example corresponds to the HMF Hamiltonian with an additional short-range interaction. The second example is a reduced Hamiltonian for dipolar layered spin structures, with a new feature with respect to the first example: the presence of anisotropies. The two examples are solved in both the canonical and the microcanonical ensemble using a combination of the min–max method with the transfer operator method. The phase diagrams present typical features of systems with long-range interactions: ensemble inequivalence, negative specific heat and temperature jumps. Moreover, for a given range of parameters, we report the signature of phase reentrance. This can also be interpreted as the presence of azeotropy with the creation of two first-order phase transitions with ensemble inequivalence, as one parameter is varied continuously.