Nanocomposites and nanomaterials

The influence of electric fields on magnetization processes of bismuth-substituted ferrite garnets
Koronovskyy V.E.
Taras Shevchenko Kiev National University, 4-g, Prospekt Glushkova Street, 03127 Kiev, Ukraine
E-mail: koron@univ.kiev.ua

Magnetoelectric (ME) properties of domain walls (DW's) in epitaxial films of bismuth-substituted ferrite garnets have been investigated by us using the optical polarimetry method [1-3]. This method allows us to measure the change of light polarization plane rotation in an external AC and DC electric field. The garnet film was placed between two optically transparent electrodes and electric field was applied to them. Optical system with a diaphragm allowed us to allocate the sites of a film of about 4 µm in diameter. A He-Ne laser (λ=0.63 µm) was used by us in experiments. We investigated bismuth-substituted ferrite garnet ﬁlms grown by liquid phase epitaxy on GGG substrate. Thickness of the ﬁlms was 7-9 µm range and thickness of the substrates for ﬁlms was about 600 µm. We detected the ME activity of DW's in external electric field in case when the area of domain structure was picked out so that DW was at the joint with optically scanned area but laser beam did not cover the DW itself. The electric-field dependences were measured at two polarities of static electric field and at fixed value of AC field. The AC electric field causes changing of the angle of light polarization plane Faraday rotation (αME) on investigated area of domain. Applying of the static electric field are activating the effect of a “tightening” of DW into the area of optical scanning. The investigated effect is sensitive to polarity of DC electric field. Reaction of the domain structure to influence of external electric fields was caused by changing the magnetic anisotropy parameters of the garnet films in an electric field.

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