Classical three-dimensional Heisenberg model with competing dynamics.

Abstract

By employing Monte Carlo simulations, we investigate the isotropic Heisenberg system model on a simple cubic lattice with short-range interactions, allowing the system to evolve toward a steady state under the influence of competition between Glauber and Kawasaki dynamics. With probability q, the system is in contact with a thermal reservoir at temperature T and evolves toward the lower energy state through Glauber dynamics. However, with probability 1-q, the system is subjected to an external energy flux that drives it toward the higher energy state through Kawasaki dynamics. By analyzing the phase diagram of T versus q, our findings show: (i) second-order phase transitions at high q and intermediate T values and first-order phase transitions below the tricritical point at (q_{t},T_{t})=(0.615±0.004,0.905±0.001), and (ii) the phenomenon of unstable self-organization in the system in which the antiferromagnetic phase is only found at q=0 with an initial antiferromagnetic state; however, as q increases at low temperatures, the system evolves to the ordered ferromagnetic phase.