Exploration of macroscopic and microscopic details in magnetoelectric composite ceramics
Muhammad Naveed-Ul-Haq, University of Duisburg-Essen, Essen, GermanyMorad Etier, University of Duisburg-Essen, Essen, GermanyHarsh Trivedi, University of Duisburg-Essen, Essen, GermanyVladimir Shvartsman, University of Duisburg-Essen, Essen, GermanySoma Salamon, University of Duisburg-Essen, Duisburg, GermanyHeiko Wende, University of Duisburg-Essen, Duisburg, GermanyDoru Lupascu, University of Duisburg-Essen, Essen, Germany
The magnetoelectric (ME) coupling is one of the fundamental mechanism for sensor design and multifield computer memories. In extrinsic multiferroics, the ME effect arises via interfacial strain between the piezoelectric and magnetostrictive phases. We outline here how the ME effect varies in composites synthesized via different synthesis routes, i.e. via the chemical nano-synthesis method and the spark plasma sintering (SPS) method. Bulk polycrystalline composites based on combinations of ferroelectric BaTiO3 and various ferrimagnetic ferrites (viz. BaFe12O19, SrFe12O19, CoFe2O4, and NiFe2O4) were studied.
The mechanical, electrical, and magnetic properties were analyzed using techniques that include X-ray diffraction (XRD), scanning electron microscopy (SEM), piezoforce response microscopy (PFM), magneto-force response microscopy (MFM), and the superconducting quantum interference device (SQUID).
It is shown that conventionally sintered BaTiO3-CoFe2O4 samples showed stronger ME effect as compared to SPS samples. Moreover, the direct and the converse ME effects were locally studied using in-situ MFM and PFM, respectively. The microscopic measurements, in conjunction with confocal Raman spectroscopy, were used to estimate the role of stress between the piezoelectric and magnetostrictive phases. The outcomes, on the whole, suggest a greater role of microstructure, as compared to that of the constituent material characteristics, in determining the persistence of the stress and hence the magnetoelectric effect within the composite. Implications on the thermodynamics of coupled problems will be discussed.
We gratefully acknowledge project funding from DFG Research Unit 1509 Ferroic Functional Materials (Lu729/12 and We2623/13).