SKM 2021 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 10: Focus Session: Higher-Order Magnetic Interactions - Implications in 2D and 3D Magnetism I
MA 10.7: Vortrag
Mittwoch, 29. September 2021, 16:15–16:30, H5
Role of higher-order exchange interactions for skyrmion stability — •Souvik Paul1,2, Soumyajyoti Haldar2, Stephan von Malottki2, and Stefan Heinze2 — 1Peter Grünberg Institute (PGI-1) and Institute for Advanced Simulation (IAS-1), Forschungszentrum Jülich, Germany — 2Institute of Theoretical Physics and Astrophysics, Christian-Albrechts-Universität zu Kiel, Germany
Magnetic skyrmions have recently become a research focus as they show promise for future magnetic memory and logic devices. One key obstacle for applications is the stability of skyrmionic bits against thermal fluctuations. The importance of Heisenberg exchange interaction, Dzyaloshinskii-Moriya interaction, magnetocrystalline anisotropy and dipole-dipole interactions in skyrmion stability has been reported. However, due to their origin from a fourth-order perturbation theory, non-Heisenberg higher-order exchange interactions (HOI) − the biquadratic, the three-site-four-spin and the four-site-four-spin interaction − have so far been neglected. Using ab-initio parametrized atomistic spin dynamics simulations in ultrathin films, we demonstrate that the HOI play an important role for skyrmion stability. We find that the effect of the first two HOI, to a large extent, can be included in the effective Heisenberg exchange constants. However, the four-site four spin interaction behaves qualitatively in a different way and has a large contribution on the energy barrier stabilizing skyrmions and antiskyrmions against annihilation. Our study opens up a new avenue for increasing the stability of topological spin structures.