Berlin 2018 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 15: Focussed Session: Geometry- and Topology-Controlled Nanoarchitectures I

HL 15.11: Vortrag

Dienstag, 13. März 2018, 12:30–12:45, EW 015

Artificial magnetoelectric materials with curvilinear helimagnets — •Oleksii Volkov, Jürgen Faßbender, and Denys Makarov — Helmholtz-Zentrum Dresden - Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Dresden, Germany.

Magnetoelectric (ME) materials are technologically relevant, e.g. as prospective non-volatile memory devices [1]. The ME effect in single-phase bulk materials is weak and observed in rather special crystals. Therefore, artificial ME materials have been proposed and are typically realized as heterostructures of magnetostrictive and piezoelectric layers. Thus, magnetic and electrical subsystems are coupled via strain. However, substrate clamping effect do not allow to achieve full change in the magnetization from zero to remanent value.

Here we propose a novel approach towards artificial ME materials with helimagnetic nanohelices embedded in a piezoelectric matrix. By applying an electric field, geometrical properties of a helical wire (i.e. pitch and radius) could be changed deterministically. In this system not relying on magnetostriction in a magnetic subsystem, pure geometrical change results in a strong modification of a magnetic state of a curvilinear helimagnet [2]. We analyse phase diagrams of magnetic and geometrical parameters, which allow us to realize switching of a magnetic state from a homogeneous (full average magnetic moment) into a periodical one (zero average magnetic moment).

[1] M. Fiebig et. al., Nature Reviews 1, 1-14 (2016).

[2] R. Streubel et. al., J. Phys. D: Appl. Phys. 49, 363001 (2016).