Characterization of Exchange-Biased CoFe/(Co,Fe)O Thin Films by Magnetometry and Ferromagnetic Resonance Techniques

Substrate and ion-bombardment effects on exchange bias were explored for CoFe/(Co,Fe)O bilayer films. The (Co,Fe)O component was sputtered onto different substrates and then ion-bombarded before a ferromagnetic CoFe layer was grown. Ferromagnetic resonance reveals that the CoFe is magnetically pinned by the (Co,Fe)O film. We find that substrate type heavily influences the magnitude of exchange bias and also the degree to which the exchange biased system is affected under ion-bombardment. In all cases there is a general decrease in the magnitude of exchange bias and coercivity, and for cases with high energy ion-bombardment unusual changes to the hysteresis loop are observed which may indicate the formation of an additional magnetic phase.