Dynamics of Domains in Diluted Antiferromagnets

TL;DR

This paper studies the relaxation dynamics of two-dimensional diluted antiferromagnets, revealing how fractal domain structures evolve over time and match theoretical predictions with simulations.

Contribution

It provides a new quantitative description of the time evolution of domain structures in disordered magnetic systems during relaxation.

Findings

Fractal domains follow a power-law size distribution with an exponential cutoff.

The derived model accurately predicts the time dependence of the order parameter.

Simulation results agree well with the theoretical description.

Abstract

We investigate the dynamics of two-dimensional site-diluted Ising antiferromagnets. In an external magnetic field these highly disordered magnetic systems have a domain structure which consists of fractal domains with sizes on a broad range of length scales. We focus on the dynamics of these systems during the relaxation from a long-range ordered initial state to the disordered fractal-domain state after applying an external magnetic field. The equilibrium state with applied field consists of fractal domains with a size distribution which follows a power law with an exponential cut-off. The dynamics of the system can be understood as a growth process of this fractal-domain state in such a way that the equilibrium distribution of domains develops during time. Following these ideas quantitatively we derive a simple description of the time dependence of the order parameter. The agreement with simulations is excellent.