This is a GOALIE proposal involving a collaboration between a physicist at Louisiana State University and collaborators at Hewlett-Packard Laboratories and Seagate Technology. The research relates to magnetic data storage devices that currently incorporate thin film giant magnetoresistive (GMR) sensors, constructed from magnetic and non-magnetic materials. Particular combinations of materials give rise to enhanced sensitivity to magnetic bits which are detected by changes in resistance. Students will be sent to HP and Seagate Laboratories to grow films, characterize their magnetic and transport properties, and develop transferable methods to compare films grown at different institutions. At LSU, the growth characteristics of the films will be evaluated with scanning tunneling microscopy, while magnetic characteristics will be evaluated using the magneto-optical Kerr effect. The electronic band structures will be characterized at the LSU Synchrotron Center for Advanced Microstructures and Devices (CAMD), using an array of synchrotron based techniques such as angle- and spin-resolved photoemission, valence-band dichroism, and Fermi surface mapping using a display analyzer. The materials studied include 3d transition metals and alloy films on single-crystal substrates such as Cu(001), or on oxides grown in situ. Theoretical studies suggest that improved sensitivity may be achieved by using half-metallic materials, such as Fe3O4 and CrO2, in spin-tunneling devices; such materials will be investigated as well. The project will provide excellent training for undergraduate and graduate students in fundamental and technical areas of condensed matter physics. %%% This is a GOALIE proposal involving a collaboration between a physicist at Louisiana State University and collaborators at Hewlett-Packard Laboratories and Seagate Technology. Magnetic sensors in computer disk drives are now being fabricated by combining atomically-thin magnetic and non-magnetic films into layered structures with improved sensitivity, allowing bit sizes to shrink and capacity to increase. The fundamental properties of the thin films differ significantly from bulk materials, however. This project focuses on experimental characterization of the new electronic structures and their relationship to the improved magnetic performance. LSU students will grow films in industrial and university facilities and characterize the magnetic and electrical characteristics of these devices. Research conducted at LSU involves atomic-scale characterization of the film growth properties using scanning-tunneling microscopy and magnetic characterization by observations of the degree to which polarized light is rotated on reflection. At the LSU Center for Advanced Microstructures and Devices (CAMD) synchrotron, students will evaluate the new electronic structures that arise by monitoring the energies and angles of electrons emitted from the surfaces under intense soft x-ray irradiation. These data will be compared with theoretical models of the electronic structure, providing the feedback that is required in the process of developing new magnetic materials. The project will provide excellent training for undergraduate and graduate students in fundamental and technical areas of condensed matter physics.
