Determination of intrinsic switching field distributions in perpendicular recording media: Numerical study of the ΔH(M,ΔM) method

Yang Liu, Karin A. Dahmen, and A. Berger
Phys. Rev. B 77, 054422 – Published 19 February 2008

Abstract

We present a numerical study of the ΔH(M,ΔM) method and its ability to accurately determine intrinsic switching field distributions in interacting granular magnetic materials such as perpendicular recording media. In particular, we study how this methodology fails for large ferromagnetic intergranular interactions, at which point the associated strongly correlated magnetization reversal cannot be properly represented by the mean-field approximation, upon which the ΔH(M,ΔM) method is based. In this study, we use a two-dimensional array of symmetric hysterons that have an intrinsic switching field distribution of standard deviation σ and ferromagnetic nearest-neighbor interactions J. We find the ΔH(M,ΔM) method to be very accurate for small Jσ values, while substantial errors develop once the effective exchange field becomes comparable with σ, corroborating earlier results from micromagnetic simulations. We furthermore demonstrate that this failure is correlated with deviations from data set redundancy, which is a key property of the mean-field approximation. Thus, the ΔH(M,ΔM) method fails in a well defined and quantifiable manner that can be easily assessed from the data sets alone.

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  • Received 8 May 2007

DOI:https://doi.org/10.1103/PhysRevB.77.054422

©2008 American Physical Society

Authors & Affiliations

Yang Liu and Karin A. Dahmen

  • Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA

A. Berger*

  • San Jose Research Center, Hitachi Global Storage Technologies, San Jose, California 95135, USA

  • *Present address: CIC nanoGUNE Consolider, E-20009 Donostia – San Sebastian, Spain.

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Issue

Vol. 77, Iss. 5 — 1 February 2008

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