Controlling the Range of Interactions in the Classical Inertial Ferromagnetic Heisenberg Model: Analysis of Metastable States

Abstract

A numerical analysis of a one-dimensional Hamiltonian system, composed by $N$ classical localized Heisenberg rotators on a ring, is presented. A distance $r_{ij}$ between rotators at sites $i$ and $j$ is introduced, such that the corresponding two-body interaction decays with $r_{ij}$ as a power-law, $1/r_{ij}^{\alpha }$ ($\alpha \ge 0$). The index $\alpha$ controls the range of the interactions, in such a way that one recovers both the fully-coupled (i.e., mean-field limit) and nearest-neighbour-interaction models in the particular limits $\alpha =0$ and $\alpha \to \infty$, respectively. The dynamics of the model is investigated for energies $U$ below its critical value ($U<U_c$), with initial conditions corresponding to zero magnetization. The presence of quasi-stationary states (QSSs), whose durations $t_{\mathrm{QSS}}$ increase for increasing values of $N$, is verified for values of $\alpha$ in the range $0\le \alpha <1$, like the ones found for the similar model of XY rotators. Moreover, for a given energy $U$, our numerical analysis indicates that $t_{\mathrm{QSS}}\sim N^{\gamma }$, where the exponent $\gamma$ decreases for increasing $\alpha$ in the range $0\le \alpha <1$, and particularly, our results suggest that $\gamma \to 0$ as $\alpha \to 1$. The growth of $t_{\mathrm{QSS}}$ with $N$ could be interpreted as a breakdown of ergodicity, which is shown herein to occur for any value of $\alpha$ in this interval.

16 pages, 7 figures

References in corpus (5)

• Statistical mechanics and dynamics of solvable models with long-range interactions
• On the diffusive anomalies in a long-range Hamiltonian system
• A closer look at the indications of q-generalized Central Limit Theorem behavior in quasi-stationary states of the HMF model
• Universal threshold for the dynamical behavior of lattice systems with long-range interactions
• Action diffusion and lifetimes of quasistationary states in the Hamiltonian Mean Field model

Cited by in corpus (2)

• First-Principle Validation of Fourier's Law: One-Dimensional Classical Inertial Heisenberg Model
• Numerical studies for an ab initio investigation into the Boltzmann prescription in statistical mechanics of large systems