Stress induced magnetic-domain evolution in magnetoelectric composites


Local observation of the stress mediated magnetoelectric (ME) effect in composites has gained a great deal of interest over the last decades. However, there is an apparent lack of rigorous methods for a quantitative characterization of the ME effect at the local scale, especially in polycrystalline microstructures. In the present work, we address this issue by locally probing the surface magnetic state of barium titante-hexagonal barium ferrite (BaTiO3-BaFe12O19) ceramic composites using magnetic force microscopy (MFM). The effect of the piezoelectrically induced local stress on the magnetostrictive component (BaFe12O19, BaM) was observed in the form of the evolution of the magnetic domains. The local piezoelectric stress was induced by applying a voltage to the neighboring BaTiO3 grains, using a conductive atomic force microscopy tip. The resulting stochastic evolution of magnetic domains was studied in the context of the induced magnetoelastic anisotropy. In order to overcome the ambiguity in the domain changes observed by MFM, certain generalizations about the observed MFM contrast are put forward, followed by application of an algorithm for extracting the average micromagnetic changes. An average change in domain wall thickness of 50 nm was extracted, giving a lower limit on the corresponding induced magnetoelastic anisotropy energy. Furthermore, we demonstrate that this induced magnetomechanical energy is approximately equal to the K-1 magnetocrystalline anisotropy constant of BaM, and compare it with a modeled value of applied elastic energy density. The comparison allowed us to judge the quality of the interfaces in the composite system, by roughly gauging the energy conversion ratio.




Science & Technology - Other Topics; Materials Science; Physics


Trivedi, H; Shvartsman, VV; Lupascu, DC; Medeiros, MSA; Pullar, RC

nossos autores


This work was supported by the European Commission within FP7 Marie Curie Initial Training Network 'Nanomotion' (grant agreement no. 290158). Support through Deutsche Forschungsgemeinschaft via Forschergruppe 1509 'Ferroic Functional Materials' (LU-729/12) is acknowledged. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. R C Pullar thanks the FCT for funding under grant IF/00681/2015. The authors would like to acknowledge Akash Raval and Dr Alexander Schwarz (Institute for Mechanics, University of Duisburg-Essen) for their assistance in calculating the electric-field under the AFM tip.

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