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arXiv · 1511.07960

Theory of Magnetic-Field-Induced Polarization Flop in Spin-Spiral Multiferroics

Masahito Mochizuki
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Abstract

The magnetic-field-induced 90-degree flop of ferroelectric polarization P in a spin-spiral multiferroic material TbMnO3 is theoretically studied based on a microscopic spin model. We find that the direction of the P-flop or the choice of +Pa or -Pa after the flop is governed by magnetic torques produced by the applied magnetic field H acting on the Mn spins and thus is selected in a deterministic way, in contradistinction to the naively anticipated probabilistic flop. This mechanism resolves a puzzle of the previously reported memory effect in the P direction depending on the history of the magnetic-field sweep, and enables controlled switching of multiferroic domains by externally applied magnetic fields. Our Monte-Carlo analysis also uncovers that the magnetic structure in the P||a phase under H||b is not a so-far anticipated simple ab-plane spin cycloid but a conical spin structure.

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Masahito Mochizuki. 2015-11-25. Theory of Magnetic-Field-Induced Polarization Flop in Spin-Spiral Multiferroics. https://doi.org/10.1103/physrevb.92.224412

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