"Understanding functional domain behavior in nanoscale magnetic heterostructures using Lorentz microscopy"
Confinement of magnetic structures geometrically as well as energetically, leads to novel and unexpected domain behavior. Lorentz transmission electron microscopy (LTEM) is ideally suited for quantitative analysis of magnetic domains and microstructure in functional nanoscale heterostructures. The current state of art LTEM enabled using aberration correctors allows for imaging down to sub-nanometer scale in field-free conditions. In this talk, the study of magnetic domain behavior in strongly interacting magnetic nanostructures namely artificial spin ices as well as functional materials that host skyrmions will be presented. Artificial spin ice lattices consist of lithographically patterned arrays of interacting magnetic islands that exhibit magnetic frustration due to geometric constraints. I will present the results on emergence of magnetic excitations in such lattices which are topologically non-trivial. Furthermore, I will discuss the effect of aperiodicity of the lattice on the magnetic frustration and a novel approach to understand such frustration based on network topology. Topologically non-trivial spin textures such as skyrmions present unique opportunities to explore exciting fundamental phenomena, such as the topological Hall effect, as well as novel applications, such as skyrmion-based spintronics. The application of LTEM to visualize and understand the magnetic spin textures in multilayer thin films as well as van der Waals materials such as Fe3GeTe2 that can host skyrmions will be discussed. Results from in-situ experiments will be presented that enable the understanding of the formation and stability of skyrmions in these materials.
