Thickness dependence of Co anisotropy in TbFe/Co exchange-coupled bilayers

Abstract

The orientation of element-specific moments was determined by using x-ray magnetic circular dichroism spectroscopy to explore exchange anisotropy of TbFe/Co bilayers. Perpendicular anisotropy of 15 Angstrom Co was induced by TbFe through exchange coupling, resulting in the out-of-plane Co moments. With increasing the thickness, Co moments were gradually tilted to the in-plane orientation because of increasing planar anisotropy. In the bilayer with thick Co, interfacial Fe moments were unidirectionally aligned in the plane, leading to in-plane exchange bias of Co. The coercivity and exchange bias field of Co in the bilayers exhibited a strong dependence on Co thickness. (C) 2004 American Institute of Physics.