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The main objective of the thesis was to construct a wide-field Kerr microscope to study all-optical helicity-dependent (AOHDS) switching in FePt nanograins. The wide- field Kerr microscope was successfully implemented into AOHDS experiments, was fully characterized and optimized for maximum image contrast. The real-time imaging and resolution of 2, 5µm enables the study of a wide range of magnetic materials and their dynamics. Moreover, a new light source, the High Lumen Density MODULE from CRY- TUR, spol. s r.o., was tested for future application in Kerr microscopy. The technical solution enabled to form a collimated beam with low divergence required for Kerr mi- croscopy. From the switching experiments on FePt nanograins, we observed a strong non-magnetic contribution to the magnetic signal, not reported in previous works. The experiments have also shown that the switching intensity depends on the laser spot size and total laser power, suggesting that the FePt grains are not entirely isolated. The grains' ensemble exhibits a more complex behavior than anticipated. 1 |
