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Microscopic model for exchange bias from grain-boundary disorder in a ferromagnet/antiferromagnet thin film with a nanocrystalline microstructure

Journal Article


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Abstract


  • Monte Carlo spin simulations were coupled to a Voronoi microstructure-generator to predict the magnitude and behavior of exchange bias in a ferromagnet/antiferromagnet (AF) thin film bilayer with a nanocrystalline microstructure. Our model accounts for the effects of irregular grain-shapes, finite-sized particles, and the possible presence of local random-fields originating from the antiferromagnet's grain-boundary regions. As the grain-boundary represents a crystal-structure distortion, we model the local effect on the exchange constants in the Gaussian approximation which can cause regions resembling a spin glass confined to an unusual 2D topology. Although an ensemble of completely disconnected AF grains isolated by non-magnetic barriers provides a small exchange bias, the introduction of a spin-glass network at the boundaries causes a four-fold enhancement in the magnitude of the loop-shift. This implies the importance of local grain-boundary behavior in defect-engineered antiferromagnets.

UOW Authors


  •   Cortie, David
  •   Biternas, A G. (external author)
  •   Chantrell, R W. (external author)
  •   Wang, Xiaolin
  •   Klose, Frank (external author)

Publication Date


  • 2014

Citation


  • Cortie, D. L., Biternas, A. G., Chantrell, R. W., Wang, X. L. & Klose, F. (2014). Microscopic model for exchange bias from grain-boundary disorder in a ferromagnet/antiferromagnet thin film with a nanocrystalline microstructure. Applied Physics Letters, 105 (3), 032402-1-032402-5.

Scopus Eid


  • 2-s2.0-84925815647

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2252&context=aiimpapers

Ro Metadata Url


  • http://ro.uow.edu.au/aiimpapers/1251

Has Global Citation Frequency


Start Page


  • 032402-1

End Page


  • 032402-5

Volume


  • 105

Issue


  • 3

Place Of Publication


  • United States

Abstract


  • Monte Carlo spin simulations were coupled to a Voronoi microstructure-generator to predict the magnitude and behavior of exchange bias in a ferromagnet/antiferromagnet (AF) thin film bilayer with a nanocrystalline microstructure. Our model accounts for the effects of irregular grain-shapes, finite-sized particles, and the possible presence of local random-fields originating from the antiferromagnet's grain-boundary regions. As the grain-boundary represents a crystal-structure distortion, we model the local effect on the exchange constants in the Gaussian approximation which can cause regions resembling a spin glass confined to an unusual 2D topology. Although an ensemble of completely disconnected AF grains isolated by non-magnetic barriers provides a small exchange bias, the introduction of a spin-glass network at the boundaries causes a four-fold enhancement in the magnitude of the loop-shift. This implies the importance of local grain-boundary behavior in defect-engineered antiferromagnets.

UOW Authors


  •   Cortie, David
  •   Biternas, A G. (external author)
  •   Chantrell, R W. (external author)
  •   Wang, Xiaolin
  •   Klose, Frank (external author)

Publication Date


  • 2014

Citation


  • Cortie, D. L., Biternas, A. G., Chantrell, R. W., Wang, X. L. & Klose, F. (2014). Microscopic model for exchange bias from grain-boundary disorder in a ferromagnet/antiferromagnet thin film with a nanocrystalline microstructure. Applied Physics Letters, 105 (3), 032402-1-032402-5.

Scopus Eid


  • 2-s2.0-84925815647

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2252&context=aiimpapers

Ro Metadata Url


  • http://ro.uow.edu.au/aiimpapers/1251

Has Global Citation Frequency


Start Page


  • 032402-1

End Page


  • 032402-5

Volume


  • 105

Issue


  • 3

Place Of Publication


  • United States