Dresden 2020 – scientific programme

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MA: Fachverband Magnetismus

MA 32: Multiferroics and Magnetoelectric Coupling I (joint session MA/KFM)

MA 32.8: Talk

Wednesday, March 18, 2020, 11:30–11:45, HSZ 401

Dielectric loss in spiral magnets — •Francesco Foggetti^1,2, Andrei Pimenov³, and Sergey Artyukhin¹ — ¹Istituto Italiano di Tecnologia, Genova, Italy — ²Università di Genova, Genova, Italy — ³Institut für Festkörperphysik, Wien, Austria

Magnetic frustration often results in non-trivial spin textures. Spiral spin structures are common in magnetic perovskites due to competing exchange interactions and may give rise to ferroelectric polarization via inverse Dzyaloshinskii-Moriya mechanism. Here we model chiral domain walls in the spiral magnetic order and characterize the excitation spectrum using a model Hamiltonian describing spins interacting with polar ionic displacements. Results suggest that high dielectric constant in spiral multiferroics (i.e. TbMnO₃, MnWO₄) originates from contributions of soft domain wall-localized electromagnons and that spiral order may play a fundamental role in the giant magneto-electric effect, observed in proximity of a phase transition from collinear antiferromagnetic order to a conical spiral in Ni₃TeO₆.