[1] Cornell Univ, Dept Mat Sci & Engn, Ithaca, NY 14853 USA
[2] Korea Atom Energy Res Inst, Div Neutron Sci, Taejon 305353, South Korea
[3] Univ Illinois, Dept Phys, Urbana, IL 61801 USA
[4] Univ Illinois, Frederick Seitz Mat Res Lab, Urbana, IL 61801 USA
[5] Penn State Univ, Dept Phys, University Pk, PA 16802 USA
[6] Penn State Univ, Mat Res Inst, University Pk, PA 16802 USA
[7] Cornell Univ, Sch Appl & Engn Phys, Ithaca, NY 14853 USA
[8] Res Ctr Julich, Peter Grunberg Inst, PGI 9 IT, JARA FIT, D-52425 Julich, Germany
[9] Kavli Inst Cornell Nanoscale Sci, Ithaca, NY 14853 USA