Doctor of Philosophy (Ph.D.)
Anne C Reilly
We have studied the exchange bias interaction in metal bilayers IrMn/Co and FeMn/Co using the static and ultrafast pump-probe Kerr effects. Experiments conducted on wedged Co samples show that the exchange bias interaction is sensitive to the buffer layers grown beneath it when the antiferromagnetic layer is FeMn. The exchange bias strength, as measured by the shift in the magnetic hysteresis loop, follows a 1/tFM dependence as reported in the literature. The time-domain pump-probe experiments reveal coherent magnetization oscillations, whose frequencies are comparable to those measured by frequency-domain FMR measurements, and they fit well to FMR equations for the frequency. We have also been able to use the pump beam to permanently alter the exchange bias interface which leads to the launching of oscillations along new geometries, particularly along the easy axis where magnetization is aligned with the applied field. This is explained qualitatively by showing that the pump has enough energy to overcome the energy barrier in the AF, allowing it to flip and provide a torque on the magnetization that launches oscillations.
© The Author
Seu, Keoki A., "Static and ultrafast MOKE studies of exchange -biased cobalt systems" (2006). Dissertations, Theses, and Masters Projects. Paper 1539623503.