Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 21: Poster I
MA 21.2: Poster
Dienstag, 13. März 2018, 09:30–13:00, Poster A
Signatures of toroidal order — •Oliver Busch1, Börge Göbel2, and Ingrid Mertig1,2 — 1Institut für Physik, Martin-Luther-Universität, D-06120 Halle — 2Max-Planck-Institut für Mikrostrukturphysik, D-06120 Halle
Magnetic moments that form a closed planar ring exhibit a toroidal moment. Ferrotoroidic order, i. e., the periodic arrangement of uniform toroidal moments, changes its sign upon application of space or time inversion and gives rise to a magnetoelectric effect of electrons [1]. Effective Hamiltonians allow a simplified description of toroidal order on honeycomb lattices and a prediction of the magnetoelectric effect, as well as a strongly diminished anomalous Hall effect in the presence of toroidal order [2].
We report on tight-binding calculations of a full sp Hamiltonian with toroidal order on a square-octagon lattice, in which toroidal moments are formed by the four spins of the square plaquettes. The band structure of electrons on this lattice without toroidal order shows a symmetric shift in reciprocal space due to spin-orbit coupling. Applying toroidal order leads to an asymmetric shift along the direction of the toroidal moment, as for the honeycomb lattice [2]. We present a band-resolved analysis to obtain deeper understanding of the above effects.
[1] N. Spaldin et al., J. Phys.: Condens. Matter 20, 434203 (2008).
[2] S. Hayami et al., Phys. Rev. B 90, 024432 (2014).