| Description: |
Exploring the rich physics of magnetic spin textures, particularly topologically non-trivial magnetic skyrmions, opens a promising pathway for the development of novel spintronic and magnonic devices. This thesis investigates the laser-induced dynamics of ferrimagnetic Fe/Gd multilayers, which host a broad variety of dipolar-stabilized magnetic spin textures at room temperature. The formation of either stripe domains, a dense lattice of topologically trivial magnetic bubbles and nontrivial magnetic skyrmions (BSKs), or a single-domain state can be controlled by adjusting the strength of an out-of-plane magnetic field. Ultrafast Kerr spectroscopy reveals the laser-induced dynamics of these magnetic spin textures, which are characterized by unique collective breathing modes enabling the unambiguous identification of stripe domains and the BSK lattice, even without resorting to imaging techniques. This thesis demonstrates versatile control of these magnetic spin textures by tuning i) the optical excitation fluence, ii) the base temperature, and iii) an external in-plane magnetic field. These control parameters enable i) the nonequilibrium nucleation and annihilation of the BSK lattice, ii) the identification of pathway-dependent ground states of magnetic spin textures within the (H,T)-phase diagram unveiling a nonadiabatic nucleation mechanism for BSKs, and iii) the significant enhancement of the proportion of skyrmions within the BSK lattice. In addition to these static control strategies, this work also showcases the possibility to directly control the spin dynamics of the BSK lattice. Employing dual-pulse excitation with variable time delay allows to initiate and to tailor the breathing mode of BSKs in both amplitude and phase. In total, this thesis explores multiple pathways for controlling dipolar-stabilized magnetic spin textures and manipulating laser-induced breathing mode dynamics. These findings provide valuable insights into the fundamental mechanisms of these processes, thereby paving the way for future ... |