Project Details
Projekt
Antiferromagnetic Skyrmions in ultra-thin oxide films
Applicant
Dr. Kirsten von Bergmann
Subject Area
Experimental Condensed Matter Physics
Term
since 2018
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 402843438
Antiferromagnetic skyrmions are promising candidates for future spintronic applications because they combine advantages of antiferromagnets, such as a vanishing magnetic strayfield and fast dynamics, with the unique properties of particle-like skyrmions. Many different materials exhibit antiferromagnetic interactions and thus may potentially host antiferromagnetic skyrmions. Several theoretical studies have highlighted that such antiferromagnetic skyrmions are expected to exhibit a motion exactly along the direction of lateral currents, in contrast to ordinary (ferromagnetic) skyrmions which are deflected. Whereas recently skyrmions in synthetic antiferromagnets, i.e. antiparallelly coupled ferromagnetic layers, and skyrmions within ferrimagnets have been reported, no experimental demonstration of an individual skyrmion in an antiferromagnetic material has yet been presented. Isolated antiferromagnetic skyrmions are always metastable objects. To stabilize such localized twisted spin textures in antiferromagnets, a favorable interplay between the relevant magnetic interactions is necessary. In contrast to ferromagnetic skyrmions their antiferromagnetic counterparts cannot be induced by external magnetic fields, thus a local manipulation between an antiferromagnetic state and the metastable antiferromagnetic skyrmion must be achieved.We have identified the material class of ultra-thin magnetic oxide films as promising for both the stabilization and the manipulation of antiferromagnetic skyrmions. Depending on the preparation conditions variable amounts of oxygen can be incorporated into the surface layers of a magnetic film, enabling a tuning of the magnetic properties in order to achieve a favorable interplay for the stabilization of antiferromagnetic skyrmions. Many ultra-thin magnetic oxide films are polar, and thus they intrinsically amplify the effect of local electric fields on the spin texture, facilitating the local manipulation of the magnetic state. We will use spin-polarized scanning tunneling microscopy at low temperatures to characterize the magnetic order of model-type ultra-thin oxide films. This experimental method is particularly suited to study atomic-scale magnetic states because it combines spin sensitivity with atomic resolution. Moreover, the probe tip will be used to locally create and annihilate particle-like antiferromagnetic skyrmions with vertical currents or electric fields.
DFG Programme
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