Visibility and Apparent Size of Néel-Type Magnetic Skyrmions in Fresnel Defocus Images of Multilayer Films. (December 2021)

• Record Type: Journal Article
• Authors: Denneulin, Thibaud; Caron, Jan; Müller-Caspary, Knut; Boulle, Olivier; Kovács, András; Dunin-Borkowski, Rafal E.
• Is Part Of: Microscopy and microanalysis. Volume 27:Number 6(2021)
• Page Start: 1356
• Page End: 1365
• Publication Date: 2021-12
• Subjects: ferromagnetism -- Fresnel defocus imaging -- Lorentz microscopy -- multilayers -- Néel-type magnetic skyrmions -- transmission electron microscopy; Microscopy -- Periodicals; Microchemistry -- Periodicals; 502.82
• DOI: 10.1017/S1431927621012927
• Languages: English
• ISSNs: 1431-9276

Abstract

Abstract: Abstract : Multilayers that comprise thin films of heavy metals and ferromagnets have been shown to host Néel-type magnetic skyrmions at room temperature. Fresnel defocus imaging in Lorentz transmission electron microscopy is a widely used technique for recording magnetic information about skyrmions. However, the visibility of Néel-type skyrmions in Fresnel defocus images is typically low, both because only a small component of their magnetic field contributes to the signal and because of the presence of diffraction contrast from the polycrystalline multilayer structure. Here, we take advantage of the out-of-plane hysteresis in such samples to record background-subtracted Fresnel defocus images. We demonstrate an improvement in magnetic signal-to-noise ratio and spatial resolution by a factor of 3 for a (Pt/Co/NiFe)×5 multilayer. We also use simulated Fresnel defocus images of Néel-type magnetic skyrmions to understand the influence of defocus on apparent skyrmion size.