Investigation of magnetization dynamics of vortices probed by high frequency scanning tunneling microscopy

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Within this project, we will investigate the magnetization dynamics of nanostructures, in particular, magnetic vortices. The measurements are based on a recently developed high-frequency scanning tunneling microscope, which exhibits time resolution down to 120 ps. This method is, so far, the only one which combines spatial resolution down to the atomic scale, high time resolution and the possibility of local excitation of the magnetic system by spin-polarized tips. This will allow to study magnetization dynamics down to the atomic scale. We will explore this novel possibility to study the response of the vortex structure to local excitations in defined distance to the vortex core or at defects. Using global excitation via striplines, we aim at a temporal imaging of the vortex dynamics with atomic resolution in order to pinpoint the influence of defects and external fields on the dynamics.We will use Fe nanoislands prepared on W(110), which exhibit a vortex at a height of about 7nm and lateral length scales of 100 nm. The preparation is performed in-situ using molecular beam epitaxy (MBE). Magnetic defects are created by atomic manipulation of foreign atoms deposited at low temperature. For the time-resolved imaging of the spin dynamics, we will prepare the magnetic nanostructures directly on a W(110) stripline.