Gemeinsames TKM-TFP Seminar

  • Datum:

    Montag, 14.00-15.30 Uhr

  • Referent:

    Garst, Mirlin, Rockstuhl, Schmalian, Shnirman

  • Ort:

    10-01

Spin-wave modes in curved 3D nanostructures

Seminar über Theoretische Festkörperphysik

Vortragender:

Attila Kakay

Datum:

20.06.2022 14:00

Ort:

Room 10.01, Bldg. 30.23 CS and Zoom

Zugehörigkeit:

Helmholtz-Zentrum Dresden-Rossendorf

Gastgeber:

Dr. Volodymyr Kravchuk

Abstract

Spin waves in magnetic nanotubes have shown interesting non-reciprocal properties in their dispersion relation, group velocity, frequency linewidth and attenuation lengths [1,2,3]. The reported chiral effects are similar to those induced by the Dzyalonshiinsky-Moriya interaction [4,5], however in curved shells the dynamic fields originating from the dipole-dipole and isotropic-exchange interactions are responsible for the curvature-induced magnetochiral effects. The isotropic-exchange interaction can also induce non-reciprocal spin-wave transport; the so-called Berry phase [6] of spin waves. A disentanglement of the dipole-dipole and exchange contributions to the non-reciprocal spin-wave propagation can be done in the thin nanotube limit, in general for the helical equilibrium state. To do so, we have analytically described the full spin-wave dispersion in cylindrical nanotubes when its equilibrium state evolves from an axial to an azimuthal magnetization state. Using our recently developed open source finite-element dynamic-matrix eigensolver, TetraX[8], we present the first results on curvature effects on spin-wave dynamics in thick magnetic membranes, where curvature leads to non-reciprocal mode hybridization due to non-reciprocal mode profiles, something which is not observed in thin curved shells. Finally, we show, that lowering the rotational symmetry of nanotubes by decreasing the number of planar facets splits an increasing number of spin-wave modes, which are doubly degenerate in cylindrical tubes. This symmetry-governed splitting is distinct form the topological split observed in cylindrical nanotubes.
[1] J. Otálora et al., Phys. Rev. Lett. 117, 227203 (2016).
[2] J. Otálora et al., Phys. Rev. B 95, 184415 (2017).
[3] J. Otálora et al., Phys. Rev. B 98, 014403 (2018).
[4] I. Dzyaloshinsky, Journal of Physics and Chemistry of Solids 4, 241 (1958). [5] T. Moriya, Phys. Rev. Lett. 4, 228 (1960).
[6] V.K. Dugaev et al., Phys. Rev. B 72, 024456 (2005). [7] Körber et al., AIP Advaances 11, 095006 (2001)
[8] https://gitlab.hzdr.de/micromagnetic-modeling/tetrax