Seminars Archive

Non-Repetitive Magnetization Dynamics in Ultra Thin magnetic Films

Abstract
In recent years there has been intensive interest and research effort in the field of magnetization dynamics. Ultra fast phenomena such as demagnetization or creation of magnetic order have been studied, typically after laser excitation and using stroboscopic pump/probe experiments. Equally important have been magnetic field induced or spin transfer torque induced phenomena, typically also studied in stroboscopic experiments. Stroboscopic imaging techniques have given insight into dynamic magnetic phenomena on picosecond time scales and several 10's of nanometers spatial scales. Much less attention has been paid to non-repetitive phenomena taking place on longer time scales between nanoseconds up to several seconds. One of the reasons is the lack of a non-repetitive magnetic microscopy method with high spatial (<100 nm) and temporal resolution (<1 ms). In this talk we will present a fast imaging technique based on the recently developed technique of threshold photoemission magnetic circular dichroism (TP-MCD) [1,2] in combination with photoemission electron microscopy (PEEM). Using this powerful method we achieve large magnetic contrast of several percent in the laboratory using circularly polarized visible light allowing us to image the domain structure of perpendicularly magnetized Fe/Ni/Cu(001) thin films. This particular magnetic system is imaged in a non-repetitive mode as a function of temperature and magnetic field. We report of domain transformations and fluctuation. 1) T. Nakagawa and T. Yokoyama, Phys. Rev. Lett. 96, 237402 (2006). 2) Kronseder et al., Phys. Rev. B 83, 132404 (2011).