Multiphase Magnetic Systems: Measurement and Simulation

TL;DR

This paper explores measurement and simulation techniques for multiphase magnetic systems, highlighting the use of FORC patterns and visualization methods to understand complex magnetic interactions and behaviors.

Contribution

It introduces a visualization method using Preisach hysteron distribution patterns to simulate multiphase magnetic behaviors and demonstrates the complexity of real materials through experimental FORC analysis.

Findings

Magnetic materials often contain multiple phases, not just a single phase.

FORC patterns can distinguish different phases and their interactions.

Simulations can reproduce complex hysteresis behaviors observed in experiments.

Abstract

Multiphase magnetic systems are common in nature and are increasingly being recognized in technical applications. One characterization method which has shown great promise for determining separate and collective effects of multiphase magnetic systems is first order reversal curves (FORCs). Several examples are given of FORC patterns which provide distinguishing evidence of multiple phases. In parallel, a visualization method for understanding multiphase magnetic interaction is given, which allocates Preisach magnetic elements as an input 'Preisach hysteron distribution pattern' (PHDP) to enable simulation of different 'wasp-waisted' magnetic behaviors. These simulated systems allow reproduction of different major hysteresis loop, FORC pattern, and switching field distributions of real systems and parameterized theoretical systems. The experimental FORC measurements and FORC diagrams of four commercially obtained magnetic materials, particularly those sold as nanopowders, shows that these materials are often not phase pure. They exhibit complex hysteresis behaviors that are not predictable based on relative phase fraction obtained by characterization methods such as diffraction. These multiphase materials, consisting of various fractions of BaFe12O19, epsilon-Fe2O3, and gamma-Fe2O3, are discussed.