[1] Hitachi Global Storage Technol, San Jose Res Ctr, San Jose, CA 95120 USA
[2] Nancy Univ, Phys Mat Lab, F-54506 Nancy, France
[3] Univ Calif Berkeley, Lawrence Berkeley Lab, Ctr Xray Opt, Berkeley, CA 94720 USA
[4] Chungbuk Natl Univ, Dept Phys, Cheongju 361763, South Korea
[5] Univ Calif Berkeley, Lawrence Berkeley Lab, Div Mat Sci, Berkeley, CA 94720 USA
[6] Univ Calif Berkeley, Lawrence Berkeley Lab, Adv Light Source, Berkeley, CA 94720 USA
[7] Univ Calif San Diego, Ctr Magnet Recording Res, La Jolla, CA 92093 USA