Ballistic current transport studies of ferromagnetic multilayer films and tunnel junctions (invited)

Three applications of ballistic electron microscopy are used to study, with nanometer-scale resolution, the magnetic and electronic properties of magn etic multilayer thin films and tunnel junctions. First, the capabilities of ballistic electron magnetic microscopy are demonstrated through an investi gation of the switching behavior of continuous Ni80Fe20/Cu/Co trilayer film s in the presence of an applied magnetic field. Next, the ballistic, hot-el ectron transport properties of Co films and multilayers formed by thermal e vaporation and magnetron sputtering are compared, a comparison which reveal s significant differences in the ballistic transmissivity of thin film mult ilayers formed by the two techniques. Finally, the electronic properties of thin aluminum oxide tunnel junctions formed by thermal evaporation and spu tter deposition are investigated. Here the ballistic electron microscopy st udies yield a direct measurement of the barrier height of the aluminum oxid e barriers, a result that is invariant over a wide range of oxidation condi tions. (C) 2001 American Institute of Physics.