AVS 49th International Symposium
    Magnetic Interfaces and Nanostructures Tuesday Sessions
       Session MI-TuP

Paper MI-TuP9
Spin Polarized Vacuum Tunneling in Field Emission from Co-Coated W(111) Tips

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Aspects of Magnetism
Presenter: K.L. Man, Hong Kong University of Science and Technology
Authors: K.L. Man, Hong Kong University of Science and Technology
R. Bryl, Hong Kong University of Science and Technology
R. Zdyb, Arizona State University
T.C. Leung, National Chung Cheng University, China
C.T. Chan, Hong Kong University of Science and Technology
E. Bauer, Arizona State University
M.S. Altman, Hong Kong University of Science and Technology
Correspondent: Click to Email
Ultrathin Co films are grown on the W(111) surface as the basis for spin polarized vacuum tunneling in field emission and scanning tunneling microscopy. The growth morphology, structure and magnetism are studied with conventional and spin polarized low energy electron microscopy (LEEM/SPLEEM) and diffraction (LEED) and first principles total energy calculations. Quasi-layer-by-layer growth of thick pseudomorphic Co films is observed at 380K, while Stranski-Krastanov growth and transformation to a (6x6) closed-packed structure are observed at higher temperatures. Pseudomorphic Co/W(111) is ferromagnetically ordered at 380K when film thickness exceeds 7.6 ML. Although only in-plane magnetization is found, a strong influence of substrate atomic steps is seen in the magnetization easy axis and magnetic domain structure. Spin polarization in vacuum tunneling is assessed by a Mott electron spin polarimeter coupled to a field emission microscope. High spin polarization (typically 20%, maximum 50%) in field emission from Co-coated W(111) tips and polarization manipulation achieved by pulsed magnetic field encourage further development.