Berlin 2018 – scientific programme
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MA: Fachverband Magnetismus
MA 57: Focus Session: Spinorbitronics – from efficient charge/spin conversion based on spin-orbit coupling to chiral magnetic skyrmions III (joint session MA/TT)
MA 57.8: Talk
Friday, March 16, 2018, 12:15–12:30, H 1012
Speed limits for Skyrmions — •Jan Müller1, Ben McKeever2,3, and Karin Everschor-Sitte3 — 1Institut für Theoretische Physik, Universität zu Köln, 50937 Köln, Deutschland — 2Graduate School Materials Science in Mainz, 55128 Mainz, Germany — 3Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Deutschland
Magnetic skyrmions are particle-like textures in the magnetization, characterized by a topological winding number. Nanometer-scale skyrmions have been observed at room temperature in magnetic multilayer structures. The combination of small size, topological quantization, and their efficient electric manipulation makes them interesting candidates for information carriers in high-performance memory devices which rely on mobile bits. Skyrmion racetrack memory devices have been suggested where skyrmions move in a one-dimensional nanostrip. The information in the racetracks is encoded either in the distance between skyrmions or in additional attributes of these, e.g. shifts from the center of the track or different winding numbers. In order to drive skyrmions along the racetrack, it is often suggested to apply spin-polarized currents. Besides moving the skyrmions, the applied currents, however, also deform them, which is usually assumed a negligible effect. We study these deformations and show that they trigger an instability which ultimately sets a speed limit in the racetracks.