Nanostructured exchange coupled hard / soft composites: from the local magnetization profile to an extended 3D simple model

TL;DR

This paper develops an extended 3D simple model to analyze exchange coupling in nanostructured hard/soft magnetic composites, linking local magnetization profiles to macroscopic magnetic properties.

Contribution

It introduces a novel extension of local interface descriptions to 3D models for nanocomposites with embedded hard crystallites.

Findings

Demonstrates the extension of interface behavior from 1D to 3D models.

Provides insights into the magnetization curve features due to exchange coupling.

Highlights the importance of nanostructure in magnetic property control.

Abstract

In nanocomposite magnetic materials the exchange coupling between phases plays a central role in the determination of the extrinsic magnetic properties of the material: coercive field, remanence magnetization. Exchange coupling is therefore of crucial importance in composite systems made of magnetically hard and soft grains or in partially crystallized media including nanosized crystallites in a soft matrix. It has been shown also to be a key point in the control of stratified hard / soft media coercive field in the research for optimized recording media. A signature of the exchange coupling due to the nanostructure is generally obtained on the magnetization curve $M(H)$ with a plateau characteristic of the domain wall compression at the hard/soft interface ending at the depinning of the wall inside the hard phase. This compression / depinning behavior is clearly evidenced through one dimensional description of the interface, which is rigorously possible only in stratified media. Starting from a local description of the hard/soft interface in a model for nanocomposite system we show that one can extend this kind of behavior for system of hard crystallites embedded in a soft matrix.