Thickness Dependence of Surface Coercivity in Polished Magnetic Oxide Platelets

Magnetic oxide platelets which have been prepared using abrasive polishing techniques can possess a high domain wall coercivity, Hc > 5 Oe, which renders them useless for device applications. The coercivity can be reduced by ion milling the platelet surfaces. The problem arises of how much material to remove to provide a useful device for a particular application. This paper describes the application of ion milling to investigate the thickness dependence of coercivity in Sm0.55 Tb0.45 FeO3 and YbFeO3 platelets. The etching rate used was 0.5μ /h/side and coercivities as low as 0.08 Oe for Sm0.55Tb0.45FeO3 and 0.4 Oe for YbFeO3 have been obtained after removal of a total of 9 μ of material from the platelet surfaces. A method for producing a guide channel for bubble domains is also described.