AVS 49th International Symposium
    Magnetic Interfaces and Nanostructures Wednesday Sessions
       Session MI-WeM

Paper MI-WeM7
In-Situ Conductance Measurements of Giant Magnetoresistive Multilayers

Wednesday, November 6, 2002, 10:20 am, Room C-205

Session: Magnetic Recording: GMR, Tunneling, and Media
Presenter: A.T. McCallum, National Institute of Standards and Technology
Authors: A.T. McCallum, National Institute of Standards and Technology
S.E. Russek, National Institute of Standards and Technology
Correspondent: Click to Email
In-situ conductance measurements can detect the changes in electronic structure during deposition of a multilayer with submonolayer resolution. Here, we present conductance verses thickness data, taken every half monolayer, for both top and bottom pinned spin valves at different temperatures. These measurements can clearly identify bulk scattering processes and interfacial scattering. For example, our data shows adding Co onto Cu adds strong interfacial scattering mechanisms. The conductance verses thickness data were compared to a Boltzmann transport equation (BTE) model. Bulk conductivities were measured by extending the measurements out to large layer thicknesses. Bulk electron mean free paths were calculated from the measured conductivites and the results of other experiments. Transmission probabilities and specular reflection probabilities were deduced from this model. The spatial distribution of current density in the multilayer, was then calculated using the BTE model. In-situ conductance measurements were used to characterize thin oxide layers, which are used as insulating barriers in magnetic tunnel junctions and specularly reflecting surfaces in giant magnetoresistance devices. For these applications it may be necessary to completely oxidize one layer of metal and not oxidize the metal underneath. The dynamics of oxidizing an Al surface were observed using in-situ conductance measurements and a vibrating crystal thickness monitor. The thickness monitor measures the oxygen uptake over time while in-situ conductance measures the amount of Al oxidized and the change in specularity due to the oxide. Using these techniques we characterized several oxidization procedures to determine the details of the oxidization process and to find an optimum oxidization procedure.