AVS 47th International Symposium
    Magnetic Interfaces and Nanostructures Tuesday Sessions
       Session MI+NS+NANO 6-TuA

Invited Paper MI+NS+NANO 6-TuA4
Magnetic Imaging by Local Tunneling Magnetoresistance - A High Resolution Technique

Tuesday, October 3, 2000, 3:00 pm, Room 206

Session: Magnetic Imaging II
Presenter: W. Wulfhekel, MPI Halle, Germany
Authors: W. Wulfhekel, MPI Halle, Germany
H.F. Ding, MPI Halle, Germany
J. Kirschner, MPI Halle, Germany
Correspondent: Click to Email
We give an overview over our recent efforts of magnetic imaging using scanning tunneling microscopy with a ferromagnetic tip. Magnetic sensitivity is obtained on the basis of local tunneling magnetoresistance between a soft magnetic tip and the sample. The imaging capacities of the technique are illustrated with exemplary studies of the surface domain structure of different itinerant ferromagnets. On Co(0001) we find surprisingly narrow sections of the walls of only 1.1nm width, over an order of magnitude less than previously observed in Co. Recording quantitative profiles of the perpendicular component of the magnetization across the wall and comparing the experimental data with micromagnetic calculation, the narrow sections are identified as 20° domain walls. Besides magnetic imaging, we focus on the influence of the stray filed of the tip on the magnetic structures under investigation. In the limit of soft magnetic materials or strong stray fields, the wall mobility and magnetic susceptibility can be studied on the local scale. Finally, measurements of magnetoresistance versus tunneling voltage and tip sample distance give deeper insight into the mechanisms of spin polarized tunneling.