[ Home |
Research |
Publications |
People |
Links |
Contact
]
Magnetization reversal in
exchange biased Co/CoO probed with anisotropic
magnetoresistance
Thomas Gredig, Ilya N. Krivorotov, and E. Dan Dahlberg
Journal of Applied Physics -- May 15, 2002 -- Volume 91, Issue 10, pp. 7760-7762
The magnetization reversal in exchange coupled polycrystalline Co/CoO bilayers has been investigated as a
function of CoO thickness using anisotropic magnetoresistance as a probe. The anisotropic magnetoresistance
(AMR) was measured during the magnetization reversal and it was used to determine the orientation of the
magnetization. For thin CoO layers large training effects were present; ergo the first hysteresis loop after
field cooling was not the same as the second. The magnitude of the observed training was found to decrease with
increasing CoO thickness. In the samples where substantial training was observed, the first magnetization
reversal was dominated by nucleation of reversed domains. For the reversal from the antiparallel state back to
the parallel direction, the AMR is consistent with a rotation process. In thicker CoO films where the training
was less, the asymmetry was drastically reduced. A simple model that couples the antiferromagnetic grains to
the ferromagnetic layer simulates qualitatively the observed magnetoresistance.