Finite driving rate effects in the nonequilibrium athermal random field Ising model of thin systems

Abstract

Thin disordered ferromagnetic systems driven by varying magnetic field represent a challenge from theoretical, experimental and technological perspective. Understanding their temporal evolution under the mutual influence of finite driving rate with which the external magnetic field changes, geometry of the sample, and the amount of disorder is a complex task. It is studied here within the framework of the nonequilibrium athermal random field Ising model which has a dynamical behavior suitable for this kind of analysis both in statistical physics and physics of magnetism. Our results, obtained by means of numerical simulations performed at a discrete time scale of the model in a wide range of driving rates and domains of disorder, unveil the rate sensitivity exhibited by the response signal and the underlying avalanche distributions, correlation functions of spin-flip events, average avalanche shapes and the values of coercive field. Due to the rate-imposed spreading of multiple avalanches during the same/partially shared intervals of time, the pertaining effective exponents turn out to be rate-dependent as well. Our findings provide new insights on some features of field driven nonequilateral systems that could be applicable for investigations of a variety of thin systems driven at finite driving rates.