Impedance spectroscopy of epitaxial multiferroic thin films



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Schmidt, Rainer and Eerenstein, Wilma and Winiecki, Thomas and Morrison, Finlay D. (2007) Impedance spectroscopy of epitaxial multiferroic thin films. Physical review B, 75 (24). ISSN 1098-0121

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Temperature dependent impedance spectroscopy enables the many contributions to the dielectric and resistive properties of condensed matter to be deconvoluted and characterized separately. We have achieved this for multiferroic epitaxial thin films of BiFeO_(3) (BFO) and BiMnO_(3) (BMO), key examples of materials with strong magnetoelectric coupling. We demonstrate that the true film capacitance of the epitaxial layers is similar to that of the electrode interface, making analysis of capacitance as a function of film thickness necessary to achieve deconvolution. We modeled non-Debye impedance response using Gaussian distributions of relaxation times and reveal that conventional resistivity measurements on multiferroic layers may be dominated by interface effects. Thermally activated charge transport models yielded activation energies of 0.60± 0.05 eV (BFO) and 0.25± 0.03 eV (BMO), which is consistent with conduction dominated by oxygen vacancies (BFO) and electron hopping (BMO). The intrinsic film dielectric constants were determined to be 320± 75 (BFO) and 450± 100 (BMO).

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© 2007 The American Physical Society. We are grateful to M. E. Vickers for helping with the x-ray analysis and to J. F. Scott and N. D. Mathur for the useful discussions. This work was funded by the Royal Society F.D.M., an EU Marie Curie Fellowship W.E., and the Leverhulme Trust R.S.. R.S. would like to thank J. Aguilar for the kind invitation for a research visit to FIME at UANL Monterrey Mexico.

Uncontrolled Keywords:Ferromagnetic perovskite BiMnO3; Room-temperature; Ferroelectric polarization; Electric polarization; BiFeO3; Heterostructures; Crystal.
Subjects:Sciences > Physics > Electricity
Sciences > Physics > Electronics
ID Code:33103
Deposited On:15 Sep 2015 11:46
Last Modified:10 Dec 2018 14:58

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