Lukas Körber
The exploration of three-dimensional architectures has recently become a focus in several research fields, including the study of ferromagnets and superconductors. Depending on the underlying order parameter and interactions, twisting and bending flat samples into curved shells can lead to many emerging effects when the bending radius is comparable to the system's characteristic length scales. Curvature-induced emergent anisotropies and magnetochiral interactions have been widely studied in ferromagnetic systems, resulting in the discovery of various fascinating phenomena such as stabilizing skyrmions and merons on Gaussian and paraboloid bumps, pinning of domain walls or suppression of the Walker breakdown.
The impact of curvature and three-dimensional shape on magnetization dynamics, namely on the propagation of spin waves, manifests itself in several aspects: For example, the curvature of magnetic shells can modify the dynamic magnetic pseudo charges. As a result, magneto-chiral symmetry breaking of magnetostatic origin can lead to asymmetric spin-wave dispersion [1], nonreciprocal spatial mode profiles and strongly modify nonlinear magnetization dynamics [2]. Moreover, a nontrivial topology of three-dimensional magnetic specimens can induce a topological Berry phase of spin waves or impose selection rules on the dynamics of magnetic textures. Lastly, achiral symmetry breaking, induced, for example, by lowering rotational symmetries, can lead to symmetry-governed splitting of degenerate modes [3,4]. This talk will focus on the aforementioned geometrical effects on magnetization dynamics and introduce numerical techniques for studying spin waves in curved magnetic shells. To this end, the finite-element micromagnetic modeling package TetraX is presented [5], which can efficiently calculate spin-wave dispersions and spatial mode profiles in various curvilinear geometries.
[1] Otálora et al, Phys. Rev. Lett. 117, 227203 (2016)[2] Körber et al, Phys. Rev. B 106, 014405 (2022)
[3] Körber et al, Phys. Rev. B 104, 184429 (2021)
[4] Körber et al, Phys. Rev. B 105, 184435 (2022)
[5] https://tetrax.readthedocs.org/