Giant Magnetoresistance in Nanogranular Magnets

TL;DR

This paper investigates how giant magnetoresistance in nanogranular magnets varies with magnetic field and temperature, revealing hysteresis effects and domain dynamics that match experimental observations.

Contribution

It introduces a combined mean-field and elastic membrane model to analyze magnetization and domain wall motion in nanogranular magnets, explaining magnetoresistance behavior.

Findings

Hysteretic magnetization at low temperatures causes double peaks in magnetoresistance.

High temperatures lead to a single peak in magnetoresistance.

Model results align well with experimental data.

Abstract

We study the giant magnetoresistance of nanogranular magnets in the presence of an external magnetic field and finite temperature. We show that the magnetization of arrays of nanogranular magnets has hysteretic behaviour at low temperatures leading to a double peak in the magnetoresistance which coalesces at high temperatures into a single peak. We numerically calculate the magnetization of magnetic domains and the motion of domain walls in this system using a combined mean-field approach and a model for an elastic membrane moving in a random medium, respectively. From the obtained results, we calculate the electric resistivity as a function of magnetic field and temperature. Our findings show excellent agreement with various experimental data.