The effect of magnetic domain boundaries displacement induced by electric field is observed in epitaxial ferrite garnet films (on substrates with the (210) crystallographic orientation). The effect is odd with respect to the electric field (the direction of wall displacement changes with the polarity of the voltage) and even with respect to the magnetization in domains. The inhomogeneous magnetoelectric interaction as a possible mechanism of the effect is proposed. DOI: 10.1134/S0021364007140093The last few years marked the great progress in the field of magnetoelectric materials [1][2][3]. The newly discovered ferroelectricity induced by spiral magnetic ordering [3][4][5][6][7] and early discovered inverse effects of electrically induced spin modulation [8-10] not only provide a deeper insight into the mechanisms of magnetoelectric coupling (the so-called inhomogeneous magnetoelectric interaction [9][10][11]) but also map out the route for electric control of micromagnetic structure in solids, the possibility predicted in 1980-ies [11] and still not realized.The best candidates for the specific character of micromagnetism in magnetoelectric materials are thin films of ferrite garnets. From the one hand they are classical object to study micromagnetism, [12][13][14][15] from the other hand they exhibit a magnetoelectric effect that is an order of magnitude greater than the corresponding effect in the classical Cr 2 O 3 magnetoelectric [16]. Electromagneto-optical effects on local areas of a ferrite-garnet film revealed that effect is vanishingly small in a homogeneously magnetized film but it increases drastically in the vicinity of domain walls. This effect was attributed to "breathing" of domain wall in electric field providing indirect evidence for the influence of electric field on micromagnetic structure [17].In this Letter we report on the direct magnetooptical observation of a new manifestation of the magnetoelectric effect, namely, the electric-field-control displacement of domain walls in ferrite garnet films, that is of interest from the fundamental point of view and opens up new possibilities for the development of multipurpose spintronic and magnetophotonic devices on a single material platform.In our experiments we used the 9.7-μm-thick epitaxial (BiLu) 3 (FeGa) 5 O 12 ferrite garnet films grown on a Gd 3 Ga 5 O 12 substrate with the (210) crystallographic orientation. The substrate thickness was about 0.5 mm. The period of the strip domain structure was 34.5μm, and the saturation magnetization was 4πMs= 53.5G. To produce a high-strength electric field in the dielectric ferrite garnet film, we used a 50μm-diameter copper wire with a pointed tip, which

The effect of magnetic domain wall motion induced by electric field is observed in epitaxial iron garnet films grown on (210) and (110) gadolinium-gallium garnet substrates. The displacement of the domain wall changes to the opposite at the reversal of electric field polarity, and it is independent of the magnetic polarity of the domains. Dynamic observation of the domain wall motion in 400 V electric pulses gives the domain wall velocity of about 50 m/s. The same velocity is achieved in a magnetic field pulse of about 50 Oe. This type of magnetoelectric effect is implemented in single phase material at room temperature.

Spiral multiferroics whose ferroelectricity is driven by spatial spin modulation attract considerable attention due to strong magnetoelectric coupling observed in them. The present paper shows that a similar mechanism is involved in the case of conventional micromagnetic structures such as domain walls. It is shown experimentally and theoretically that the domain wall in iron garnet films has electric polarization which can be switched by an external magnetic field. From the practical application standpoint it provides an intriguing opportunity of micromagnetic structures controlled by an electric field in low-power-consumption spintronic and magnonic devices.

This paper briefly reviews research of the magnetoelectric materials and multiferroics as domain-structured media. The review is focused on magnetoelectric phenomena in epitaxial iron garnet films (electrically induced displacement and tilting of domain boundaries) as a striking example of magnetoelectricity in micromagnetism. The paper also considers the effect of an electric field on other topological defects in magnetically ordered media, including Bloch lines and Bloch points at domain boundaries, magnetic vortices, and skyrmions.

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