Magneto-transport properties of dilute granular ferromagnets

TL;DR

This study investigates the magnetoresistance behavior of dilute granular ferromagnetic Ni films near electrical percolation, revealing sharp resistance jumps linked to magneto-mechanical distortions in individual grains.

Contribution

It provides new insights into magnetostriction effects at the nanoscale in granular ferromagnetic films and introduces a method to probe grain-level distortions via magnetoresistance measurements.

Findings

Sharp resistance jumps observed as a function of magnetic field.

Magneto-mechanical distortions in single grains cause resistance changes.

Provides a measure of magnetostriction effects in nano-grain structures.

Abstract

We present magnetoresistance (MR) measurements performed on quench condensed granular Ni thin films which are on the verge of electric continuity. In these systems the electric conductivity is believed to be governed by the resistance between a very small number of grains. The films exihibit sharp resistance jumps as a function of magnetic field. We interpret these findings as being the result of magneto-mechanical distortions that occour in single grains which act as bottlenecks in the dilute percolation network. The observed features provide a unique measure of magnetostriction effects in nano-grain structures as well as being able to shed light on some of the properties of regular granular magnetic films.