In this work we present a systematic study on the variation of the magnetic properties and thermal stability of IrMn/CoFeB bilayers as a function of the post-deposition annealing temperature Tann. Both the exchange field and the blocking temperature increase linearly with Tann. This is attributed to an increase in the energy barrier in the antiferromagnetic grains which may be due to an increase in grain size or improved crystallinity, that takes place during annealing. However, the coercivity drops dramatically above T-ann > 300 degrees C indicating different origins for the uniaxial and unidirectional anisotropies. (C) 2006 Elsevier B.V. All rights reserved.
- exchange bias
- grain size