Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 25: Skyrmions I (joint session MA/TT)

TT 25.11: Vortrag

Dienstag, 17. März 2020, 12:30–12:45, POT 6

Universality of energy barriers of large magnetic skyrmions — •Jan Masell — Center for Emergent Matter Science RIKEN, Wako, Saitama, Japan

Magnetic skyrmions can only decay via singular spin configurations. We analyze the corresponding energy barriers of skyrmions for two distinct stabilization mechanisms, i.e., Dzyaloshinskii-Moriya interaction (DMI) and competing interactions [1]. Based on our numerically calculated collapse paths on an atomic lattice, we derive analytic expressions for the saddle-point textures and energy barriers of large skyrmions. The sign of the spin stiffness and the sign of fourth-order derivative terms in the classical field theory determines the nature of the saddle point and thus the height of the energy barrier. In the most common case for DMI-stabilized skyrmions (positive stiffness and negative fourth-order term) the saddle-point energy approaches a universal upper limit described by an effective continuum theory. For skyrmions stabilized by frustrating interactions, the stiffness is negative and the energy barrier arises mainly from the core of a singular vortex configuration.

[1] B. Heil, A. Rosch, and J. Masell, Phys. Rev. B 100, 134424 (2019)