Micromagnetic model of exchange bias: Effects of structure and AF easy axis dispersion for IrMn/CoFe bilayers

W. Daeng-Am, P. Chureemart, A. Rittidech, L. J. Atkinson, R. W. Chantrell, J. Chureemart

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Abstract

A micromagnetic model of an exchange bias bilayer is used to examine the impact of the physical structure and the easy axis dispersion of the antiferromagnetic (AF) layer on the exchange bias field (HEB) in an IrMn/CoFe system. Because of the different timescales, the magnetization dynamics of the IrMn and CoFe layers are modelled using respectively a kinetic Monte Carlo (kMC) approach and Landau-Lifshitz-Gilbert (LLG) equation. The easy axis dispersion is modelled using a Gaussian distribution. The calculations show that HEBincreases with increasing IrMn thickness and grain size, in agreement with experimental work. Moreover, the model allows the visualization of the switching process at the micromagnetic level to reveal the reversal mechanism. We find that the effect of AF easy axis distribution not only strongly affects the reduction of HEBbut also drives non-coherent behaviour in the reversal mechanism. This confirms that the easy axis distribution is an important factor with strong impact on the magnetic properties and exchange bias field of an exchange bias system.

Original languageEnglish
Article number045002
Number of pages8
JournalJournal of Physics D: Applied Physics
Volume53
Issue number4
Early online date18 Nov 2019
DOIs
Publication statusPublished - Jan 2020

Bibliographical note

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Keywords

  • Easy axis distribution
  • Exchange bias field
  • Kinetic monte carlo
  • Landau-lifshitz-gilbert equation

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