MAGNETIZATION REVERSAL IN COCRPT THIN-FILM TRILAYERS

Evidence for the existence of magnetic interactions between layers in a CoCrPt/Cr trilayer system is presented. From the major hysteresis lo ops and demagnetizing remanence curves we find that the initial magnet ic layer has the highest coercivity and switches quasi-independently, whereas cooperative effects are present in subsequent layers. This dif ference in behaviour is attributed to the comparatively thick (500 Ang strom) Cr underlayer on which the initial layer is sputtered. The two upper films which constitute an effective bilayer of variable spacer, X, (10 Angstrom less than or equal to X less than or equal to 100 Angs trom) appear to be coupled by a dipolar interaction between the two ma gnetic layers, It is postulated that this coupling arises from the pre sence of magnetic domains. If the system is re-magnetized from the AC demagnetized state and the remanence examined, all three films show ev idence of coupling. Once again we conclude that this is mainly dipolar in nature and arises from the presence of a domain structure in all t hree magnetic layers.