Threshold-induced correlations in the Random Field Ising Model

Sanja Janićević,Dragutin Jovković,Djordje Spasojević,Lasse Laurson

doi:10.1038/s41598-018-20759-6

Abstract

We present a numerical study of the correlations in the occurrence times of consecutive crackling noise events in the nonequilibrium zero-temperature Random Field Ising model in three dimensions. The critical behavior of the system is portrayed by the intermittent bursts of activity known as avalanches with scale-invariant properties which are power-law distributed. Our findings, based on the scaling analysis and collapse of data collected in extensive simulations show that the observed correlations emerge upon applying a finite threshold to the pertaining signals when defining events of interest. Such events are called subavalanches and are obtained by separation of original avalanches in the thresholding process. The correlations are evidenced by power law distributed waiting times and are present in the system even when the original avalanche triggerings are described by a random uncorrelated process.

Highlights

We present a numerical study of the correlations in the occurrence times of consecutive crackling noise events in the nonequilibrium zero-temperature Random Field Ising model in three dimensions
Our results demonstrate that when a thresholding procedure is applied to a Random Field Ising model (RFIM) signal at T = 0, temporal correlations emerge between the avalanches
These correlations are detectable in a form of power-law distributed waiting times and are a result of original avalanches being separated into subavalanches due to the thresholding

Summary

Introduction

We present a numerical study of the correlations in the occurrence times of consecutive crackling noise events in the nonequilibrium zero-temperature Random Field Ising model in three dimensions. Our findings, based on the scaling analysis and collapse of data collected in extensive simulations show that the observed correlations emerge upon applying a finite threshold to the pertaining signals when defining events of interest Such events are called subavalanches and are obtained by separation of original avalanches in the thresholding process. In this model, when the external magnetic field slowly changes, the system relaxes in spin-flipping avalanches, causing abrupt and jerky jumps of magnetization This type of response to the external perturbation by means of a characteristic intermittent avalanche-like relaxation is immanent in many different physical systems exhibiting crackling noise[15]. To the recently reported case of the other crackling noise system of crack line propagation[30], we find that the waiting time distribution, upon a process of thresholding, becomes of a power law type, indicating the onset of the apparent correlations in the system

Methods

Results

Conclusion