Topological Nernst effect of individual skyrmions

• Applicant: Privatdozent Dr. Hans-Werner Schumacher
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 462692865

Skyrmions are nano scale vortex like topological spin structures which can appear in magnetic materials due to competition of symmetric and antisymmetric exchange interaction. While electrical detection and manipulation of skyrmions has been heavily investigated over the last years the thermoelectrical characterization of skyrmion systems is still in its infancy. Recently, in own previous work the thermoelectrical signal of single skyrmions has been measured for the first time. However, despite the topological nature of the skyrmions no convincing evidence for the presence of a topological Nernst effect was present in the experimental data. Therefore, the goal of this project is to experimentally measure and characterize for the first time the topological Nernst contributions of individual skyrmions in a variety of material systems. To achieve this, skyrmionic thin films will be patterned into micro and nano devices and thermoelectrically characterized. Magnetic force microscopy and other imaging techniques will be used to determine and manipulate the number of skyrmions in the devices in-situ. Based on that the exact number, sizes, and details of the magnetic structure of the skyrmions under investigation will be derived and deviations from the expected anomalous Nernst effect will be pinpointed. Additionally, the imaging will allow to seek evidence for skyrmion motion induced by thermal gradients and hence for thermally induced torques. Such thermoelectrical characterization of skyrmion systems and devices and the study of their response to thermal gradients could not only enable a deep insight into the fundamental physics of coupled heat-, charge-, and spin-currents in topologically protected spin systems but might also provide new tools for the detection and thermally induced manipulation of individual skyrmions.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2137: Skyrmionics: Topological Spin Phenomena in Real-Space for Applications
• International Connection: France
• Cooperation Partner: Vincent Cros, Ph.D.