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

Invited Paper MI+NS+NANO 6-TuA9
Ballistic Electron Magnetic Microscopy Studies of Ferromagnetic Films and Tunnel Junctions

Tuesday, October 3, 2000, 4:40 pm, Room 206

Session: Magnetic Imaging II
Presenter: W.H. Rippard, Cornell University
Authors: W.H. Rippard, Cornell University
A.C. Perrella, Cornell University
R.A. Buhrman, Cornell University
Correspondent: Click to Email
A new magnetic imaging technique, ballistic electron magnetic microscopy (BEMM), has been developed to study the magnetic structure in ferromagnetic multilayer films and nanostructures as a function of magnetic field H. In BEMM we exploit the hot electron transport properties of the ferromagnetic films in order to probe their magnetic structure. This technique allows not only the magnetic imaging in applied fields with nm-scale spatial resolution, but also allows the direct investigation of spin dependent transport through the ferromagnetic multilayers. As we are not using a magnetic probe to image these films, we are able to investigate very thin and soft magnetic structures which are the most relevant to technological applications. The magnetization reversal process of both continuous and patterned ferromagnetic films have been investigated. Using a UHV compatible stencil-mask technique, sub-micron structures have been fabricated and imaged with BEMM. In particular, I will discuss the switching behavior of permalloy 'diamonds' and 'rectangles' (1.5 x 0.3 microns2), as well as other shapes of smaller dimension. Using this technique the nanometer scale imaging of tunnel junctions can also be performed. Ballistic current transport through magnetic tunnel junctions will be presented, both in terms of the imaging of 'pin holes' in the junctions and spin-dependent transport through the barrier. The energy dependence of the transport in the ferromagnetic multilayer structures as well as in the tunnel junction systems will also be presented.