Coercivity and Switching Field- Engineered Magnetic Multilayers for 3-D Patterned Media

We demonstrate the use of an exchange-biased magnetic multilayer structure as a promising basis for developing a three-dimensional-patterned storage medium. The behavior of several multilayered structures is investigated. The structures are of the form Si(001)/Ta/Co/Ta/Co/FeMn/Ta/Co/FeMn/Ta. The memory state is determined by the orientation of the magnetization of each magnetic layer. In order to achieve the independent switching of the magnetic layers necessary to set the state of the three-dimensional (3-D) "memory," the switching field and coercivity are controlled by making use of the increased coercivity and exchange biasing that result from coupling an antiferromagnetic layer to a ferromagnetic layer, and by varying the thickness of each magnetic layer. The change in behavior upon patterning the exchange-biased continuous multilayered films into arrays of 50-mum diameter dots, is investigated. We find that patterning on this scale dramatically changed the switching behavior of the magnetic layers