Tuneable exchange-spring stiffness in amorphous magnetic trilayer structures

Abstract

We investigate the magnetic properties of amorphous Sm10Co90/Co60(Al70Zr30)40/Co85(Al70Zr30)15 exchange-spring magnet trilayers. The magnetically soft Co85(Al70Zr30)15 layer is coupled to the magnetically hard Sm10Co90 layer through the weakly magnetic low-T c Co60(Al70Zr30)40 spacer layer. The strength of the coupling can be controlled with temperature and the coupling persists above the intrinsic T c of the spacer layer due to a long-range magnetic proximity effect. Polarized neutron reflectivity is used to examine the magnetic profile of the trilayers during magnetization reversal. A two-step switching occurs, with the switching angle of the soft layer strongly dependent on the strength of the coupling. In the strong coupling regime a magnetic state can be achieved where the soft layer magnetization is perpendicular to the hard layer whereas in the weak coupling regime the soft layer reverses fully.