Magnetoelectric control of domain walls in a ferrite garnet film

Abstract

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

Phase transitions in multiferroic BiFeO3crystals, thin-layers, and ceramics: enduring potential for a single phase, room-temperature magnetoelectric ‘holy grail’

“…Like the Dzyaloshinskii-Moriya-like exchange (1a), this inhomogenous interaction is magnetoelectric in origin and a spin cycloid is only possible in the presence of spontaneous polarization. It is remarkable that inhomogenous magnetoelectric interaction (2) can explain magnetoelectric effect in magnetic domain walls [31][32][33] and ferroelectricity in spiral magnets [34] under the assumption of polarization induced by magnetic inhomogeneity. Furthermore, there is a profound analogy between spatially modulated spin structures in multiferroics, and spatially modulated structures in nematic liquid crystals [35,36].…”

Magnetic domain wall motion triggered by electric field

“…The magnetooptical technique in Faraday geometry was used to observe the micromagnetic structure (the experimental details are described elsewhere [4]). We registered the magnetization distribution in initial state and the position of domain wall with static 3 Author to whom any correspondence should be addressed. 1) and did not depend on the magnetic polarity of the domain over which the tip was located.…”

“…However the spin transfer also requires large current densities of 10 6 -10 7 A/cm 2 . In [3,4] we proposed the new approach to the problem of electrically controlled magnetic state: the electric field driven domain wall motion. It was implemented in epitaxially grown single crystal iron garnet films at room temperature.…”

“…It was implemented in epitaxially grown single crystal iron garnet films at room temperature. The characteristic features of the effect evidenced for its magnetoelectric nature [3]. This paper is focused on the experimental search for means to maximize this effect and theoretical analysis of it.…”

Magneto-Electric Control of Surface Anisotropy and Nucleation Modes in L1<inline-formula><tex-math> $_{0}$</tex-math></inline-formula>-CoPt Thin Films

“…Numerical methods to study the effect of electric fields on dynamical magnetic properties in magneto-electric materials are being developed [Fischbacher 2011], and it has also been shown that dynamical effects such as domain-wall motion can be modified via electric control of intrinsic magnetic properties [Lahtinen 2012, van deWiele 2014 and ferrite garnet films [Logginov 2007]. Recently, magnetization switching due to picosecond electric field pulses in MgO/FePt/Pt(0 0 1) films has been predicted using first principle and micromagnetic simulations [Zhu 2014].…”