MINT Seminar Page

MINT seminars (EE 8192), Spring 1999

Title: ANISOTROPIC MAGNETORESISTANCE AS A PROBE OF MAGNETIZATION ROTATION IN FERROMAGNETIC/ANTIFERROMAGNETIC BILAYERS
Presenter: Chris Merton, Post Doctorate, Physics Department, University of Minnesota
Date: May 7, 1999, Friday
Time: 1:25 P.M.
Room: 102 Mech. Eng.

Abstract

Although the direct exchange between a ferromagnetic and an antiferromagnet has been known to effect a unidirectional coupling for forty years, a fundamental understanding is lacking. We recently discovered that this is due in part because the traditional technique used to measure the coupling energy, a shift in the hysteresis loop, was an incorrect measure. Better techniques consist of reversible rotations of the magnetization. The techniques we pioneered used either the anisotropic magnetoresistance (AMR) or the ac susceptibility to determine the energy. The reversible techniques result in exchange energies larger by as much as a factor of ten over the irreversible hysteresis loop technique. In addition, in a thick ferromagnetic film, with the ferromangetic spins pinned only at the ferro/antiferro interface, it is possible to use the AMR to study the average rotation of the spins through the thickness of the film. This is similar to the creation of a magnetic domain wall and provides a unique opportunity to study the energetics of domain wall formation. This may also be useful in a number of magnetic sensor applications.

For more information on the seminars, please call Jack Judy at 612/625-7381 or email at judy@ece.umn.edu