High-frequency magnetism: GHz and THz dynamics in thin films
Molecular Physics seminar
Monday 08 September 2014
to 11:00 at
Stefano Bonetti (Molecular Physics Division)
Much of the research in modern magnetism deals with the understanding of how to manipulate the building blocks of magnetic elements, spins, at the highest possible rate with the lowest possible energy consumption. Such research has direct applied consequences in information technology, but it is also leading to a new understanding of the fundamentals of magnetism.
In this talk, I will present our recent experimental results on high-frequency dynamics in magnetic metallic thin films. At first, I will present the first time-resolved images of GHz spin waves at the nanoscale. The data was taken using an x-ray microscope at SSRL, the synchrotron light source at SLAC National Accelerator Laboratory. These unique images revealed details not yet predicted by existing theories, in particular the formation of a new dynamical magnetic object. Then, I will move to a second experiment, where we used strong THz radiation to induce magnetization dynamics in a thin CoFeB layer capped by Pt. Because of the strong spin-orbit interaction in Pt, it has been recently demonstrated that the magnetization of the CoFeB layer can be manipulated using pure spin currents, without the need for dissipative charge currents. Our measurements indicate that the creation of such spin currents by means of THz radiation may not only be a faster, but also a more efficient way to control the magnetization of a thin film.
Finally, since we plan to set-up a laser-based THz source at Albanova, I will give an overlook of the many opportunities that THz science has to offer.