AVS 49th International Symposium
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI+SS-ThM

Paper MI+SS-ThM9
Probing Buried Interfaces with Soft X-ray Standing Wave Spectroscopy: Application to the Fe/Cr Interface

Thursday, November 7, 2002, 11:00 am, Room C-205

Session: Magnetic Spectroscopies
Presenter: S.-H. Yang, Lawrence Berkeley National Laboratory
Authors: S.-H. Yang, Lawrence Berkeley National Laboratory
B.S. Mun, Lawrence Berkeley National Laboratory
N. Mannella, University of California, Davis
S.K. Kim, Lawrence Berkeley National Laboratory
J.B. Kortright, Lawrence Berkeley National Laboratory
J. Underwood, Lawrence Berkeley National Laboratory
F. Salmassi, Lawrence Berkeley National Laboratory
E. Arenholz, Lawrence Berkeley National Laboratory
A. Young, Lawrence Berkeley National Laboratory
Z. Hussain, Lawrence Berkeley National Laboratory
M.A. van Hove, Lawrence Berkeley National Laboratory
C.S. Fadley, University of California, Davis
Correspondent: Click to Email
We will discuss a novel type of non-destructive method for spectroscopically studying buried nanometer-scale interfaces and other nanostructures with soft x-ray standing waves. Strong standing waves with a period of 4.0 nm and approximately 3:1 contrast ratios are created via Bragg reflection from a synthetic multilayer of form [B4C/W]40. By growing a wedge-shaped Fe/Cr bilayer on top of this multilayer, the mechanical translation of the sample exposed to a fixed and finely focussed synchrotron radiation beam is converted into a translation of the standing wave through the interface. Analyzing various core photoelectron intensities as a function of angle and beam position permits deriving layer thicknesses and interface mixing/roughness scales. Magnetic circular dichroism in photoemission from the 2p and 3p levels of Fe and Cr further permits deriving the positions and widths of regions with decreased (increased) ferromagnetic alignment for Fe (Cr), showing that normally antiferromagnetic Cr becomes ferromagnetic just below the center of the interface but with antiparallel alignment with respect to Fe, and that the equal-concentration region in the center of the interface strongly inhibits magnetic alignment for both species along the direction of net magnetizations that is probed. The magnetically-altered regions in both metals are only 1-2 atomic layers in thickness. 3s spectra from Fe and Cr further indicate that the local spin moments on both atoms do not change on crossing the interface. This standing wave-plus-wedge method should have a range of applications for the characterization of magnetic and non-magnetic nanostructures and their interfaces. Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences Division, under Contract No. DE-AC03-76SF00098.