Fig. 2: Magnetic imaging of Fe5GeTe2 in the pre-cooling phase, revealing skyrmionic spin structures.
From: Skyrmionic spin structures in layered Fe5GeTe2 up to room temperature
a Phase shift image obtained using off-axis electron holography at T = 200 K and B = 0 mT in Fe5GeTe2 with the c-axis perpendicular to the image plane after previously applying out-of-plane fields up to B = 566 mT. b Corresponding color-coded magnetic induction map where the direction of the magnetic field is given by the color wheel. Type-II as well as type-I bubbles with opposite winding numbers are present. c Schematic illustration of type-I and type-II bubbles. d Series of Fresnel images taken at various temperatures and external out-of-plane fields (parallel to the c-axis) with a defocus of −1 mm, in a ≈ 100 nm thick plan-view lamella (c-axis is perpendicular to the image plane). The magnetization within the magnetic bubbles opposes the external field, whereas the areas the magnetization between the bubbles are parallel to the field. Bubbles begin to form at higher external fields for lower temperatures.
