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Probing the exchange bias in Co/CoO nanoscale antidot arrays using anisotropic magnetoresistance
 

Summary: Probing the exchange bias in Co/CoO nanoscale antidot arrays
using anisotropic magnetoresistance
D. Tripathy and A. O. Adeyeye*
Department of Electrical and Computer Engineering, Information Storage Materials Laboratory,
National University of Singapore, Singapore 117576
Received 28 October 2008; published 18 February 2009
The dependence of exchange bias in polycrystalline Co/CoO nanoscale antidot arrays on temperature and Co
layer thickness tCo has been systematically probed using the anisotropic magnetoresistance technique. Our
experimental results reveal a relatively small degree of asymmetry in the magnetization reversal process of the
antidot arrays as compared to a continuous film of identical composition, attributable to the configurational
anisotropy of the antidot arrays and the competition between interfacial ferromagnetic-antiferromagnetic FM-
AFM exchange anisotropy and FM uniaxial anisotropy. The strong interplay between thermal activation
effects and AFM domain size confinement in the antidot arrays results in the exchange bias field HE being
either smaller or larger than the continuous film depending on the temperature. Furthermore, with increasing
tCo, the asymmetry in the magnetization reversal of the antidot arrays increases monotonously due to enhance-
ment in the FM anisotropy. This enhancement is accompanied by a reduction in the magnitudes of HE and
coercive field HC with increasing tCo at all temperatures.
DOI: 10.1103/PhysRevB.79.064413 PACS number s : 75.75. a, 73.43.Qt, 75.60.Jk, 75.70.Cn
I. INTRODUCTION
There has been sustained interest in the exchange bias

  

Source: Adeyeye, Adekunle - Department of Electrical and Computer Engineering, National University of Singapore

 

Collections: Physics; Materials Science