Distribution of switching fields in magnetic granular materials

• Published in: Applied physics letters Vol. 101; no. 18
• Main Authors: Hovorka, O., Pressesky, J., Ju, G., Berger, A., Chantrell, R. W.
• Format: Journal Article
• Language: English
• Published: 29-10-2012
• Subjects: Activation analysis; Computer simulation; Fluctuation; Granular materials; Mathematical analysis; Monte Carlo methods; Recording; Switching
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4765085

We present analytical calculations and kinetic Monte-Carlo modeling of rate-dependent behavior of switching field distributions (SFDs) in an ensemble of Stoner-Wohfarth particles, assuming distributions of anisotropies and volumes, and thermal activation included by the Néel-Brown theory. By applying probabilistic arguments, we show that the SFD can be self-consistently separated into the contribution from distributions of intrinsic properties of particles and the (irreducible) contribution resulting solely from thermal fluctuations, which is shown to become a significant effect at sweep rates relevant to the recording process. This provides a unifying framework for systematic analysis of different classes of systems.