PhD: Stability and dynamics of different 3D spin textures in multilayers

In this PhD thesis, we propose to investigate experimentally the physics of discretized 3D partial skyrmion tubes or of 3D cocoons - the simplest siblings of skyrmions in magnetic multilayer materials. This PhD proposal is motivated by our recent observation of such 3D states in aperiodically stacked multilayers and by our hypothesis that the same states are responsible for the phenomenon of ultrafast laser-induced topological phase transitions by serving as catalysts to overcome the otherwise prohibitively strong topological energy barriers in 2D systems. Our goal is to validate this hypothesis and to uncover the basic physical properties of discretized 3D partial skyrmions on the way. Our approach is characterized by interdisciplinarity between the fields of materials science (exploring the stability phase space), highly advanced coherent x-ray imaging (resolving the 2D and 3D spin textures in collaboration with synchrotron teams), spintronics (confirming the quasi-particle properties of 3D partial skyrmions through their spin-orbit torque driven motion) and ultrafast science (tracking the transient gradient of magnetic properties and the vertical propagation of topological switching after ultrafast laser exposure). This PhD is part of a joint ANR/DFG project “Topo3D” with some strong collaboration with N. Jaouen from SOLEIL Synchrotron and Felix Büttner from Augsburg University and HBI, Berlin, Germany.