Submicron Size Particles of Magnetic Films and Multilayers

Abstract

The area between the micro- and macroscopic ranges of magnetism offers an exciting field for research and development. The design of magnets for small-scale applications requires several physical parameters to be simultaneously controlled and matched to each other. First one should control the exchange energy, the crystalline anisotropy and the atomic magnetic moment; material parameters governing e. g. the ordering temperature and magnetization of the material. This may be accomplished by applying modern preparation techniques to make thin films and layered materials, yielding a variety of intrinsic magnetic properties [1]. Second, the demagnetizing effects that are inevitably introduced when the lateral extensions of the material are limited must be incorporated in the design to yield the proper zero-field state as well as dynamic response [2]. There are many questions to answer about the zero-field state of a magnetic particle, for instance how the critical sizes for formation of a single domain (SD) can be reached. SD particles with two possible orientations of their moment in zero field — a binary bit — are suggested as building blocks of a novel magnetic memory [3]. At the same time as a stable zero-field state is obtained, magnetization reversal should occur at an appropriate field with a narrow distribution of switching fields among the particles.