Uncovering Chirality of Skyrmions in Polycrystalline B20 FeGe on Si

Understanding chirality, the intrinsic handedness of a system, is important for future technologies using quantum magnetic materials. Of particular interest are magnetic skyrmions which are chiral and topologically protected, meaning that their spin textures can act as barriers from deformation in crystalline grains. However, most electron microscopy studies use Lorentz TEM or holography to investigate chirality of skyrmions in nearly perfect single crystals because Fresnel effects may cause signals from grain structures to be mistaken as magnetism when the two are comparable in size. In this work, we probe nanomagnetism of topological magnetic textures in sputtered thin film of B20 FeGe on Si to study the relationship between magnetic and crystal chirality. Using 4D-STEM, we find that the vorticity and helicity of these magnetic topological phases are coupled to the crystal chirality. Furthermore, our work shows that signals from magnetism can be disentangled from the crystalline effects for sub-micron grains, enabling a way to investigate topological magnetism in the presence of small polycrystalline grains. This methodology is important for spintronics and low-power magnetic memory technologies that rely on scalable techniques for large scale manufacturing of real devices.<br/><br/>[1] Nguyen, KX et al.,<i> Physical Review Applied</i>, 17, 034066 (2022).