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MA: Fachverband Magnetismus

MA 10: Skyrmions I (joint session MA/KFM/TT)

MA 10.4: Vortrag

Montag, 12. März 2018, 16:00–16:15, EB 301

Entropy limited topological protection of skyrmions in Fe_1−xCo_xSi — Johannes Wild¹, •Thomas Meier¹, Simon Pöllath¹, Matthias Kronseder¹, Andreas Bauer², Alfonso Chacon², Marco Halder², Marco Schowalter³, Andreas Rosenauer³, Josef Zweck¹, Jan Müller⁴, Achim Rosch⁴, Christian Pfleiderer², and Christian Back¹ — ¹Institut für experimentelle und angewandte Physik, Universität Regensburg — ²Physik-Department, Technische Universität München — ³Institut für Festkörperphysik, Universität Bremen — ⁴Institut für Theoretische Physik, Universität zu Köln

Topologically protected magnetic textures in materials with broken inversion symmetry are considered as future high-density data storage media. The life time of these textures therefore plays a crucial role for data retention. We have used Lorentz transmission electron microscopy to infer the energetics of the topological decay of magnetic skyrmions far from equilibrium in the chiral magnet Fe_1−x Co_x Si. We investigated the decay of a lattice of sykrmions at different magnetic fields and temperatures by imaging the magnetic configuration of the system in real-time with a high speed camera. We observed that the skyrmion life time τ extracted from these movies depends exponentially on temperature following an Arrhenius law, τ ∝ τ₀ exp(Δ E/k_B T). The prefactor τ₀ of this Arrhenius law changes by more than 30 orders of magnitude for small changes of magnetic field reflecting a substantial reduction of the life time of skyrmions by entropic effects and thus an extreme case of enthalpy-entropy compensation.