Roman V. Petrov

Electromechanical Resonance in Magnetoelectric Composites: Direct and Inverse Effect

Magnetoelectric (ME) coupling in the composites is mediated by the mechanical stress and one would expect orders of magnitude stronger coupling when the frequency of the ac field is tuned to acoustic mode frequencies in the sample than at non-resonance frequencies. A model is presented for the increase in ME coupling in magnetostrictive-piezoelectric bilayers for the longitudinal, radial, and bending modes in the electromechanical resonance region. We solved the equation of medium motion taking into account the magnetostatic and elastostatic equations, constitutive equations, Hookes law, and boundary conditions. We estimated the ME voltage coefficient for direct ME effect and ME susceptibility for inverse ME coupling. The frequency dependence of the ME voltage coefficient and ME susceptibility reveals a resonance character in the electromechanical resonance region. Then we considered ME interaction in the magneto-acoustic resonance region at the coincidence of electromechanical and magnetic resonance. Variation in the piezomagnetic coefficient with static magnetic field for magnetic layer results in a dependence of ME voltage on applied bias magnetic field. As an example, we considered specific cases of cobalt ferrite or yttrium-ferrum garnet - lead zirconate titanate and nickel/permendur - lead zirconate titanate bilayers. Estimated values of ME voltage coefficient versus frequency profiles are in agreement with data.

Magnetoelectric Current Sensors

In this work a magnetoelectric (ME) current sensor design based on a magnetoelectric effect is presented and discussed. The resonant and non-resonant type of ME current sensors are considered. Theoretical calculations of the ME current sensors by the equivalent circuit method were conducted. The application of different sensors using the new effects, for example, the ME effect, is made possible with the development of new ME composites. A large number of studies conducted in the field of new composites, allowed us to obtain a high magnetostrictive-piezoelectric laminate sensitivity. An optimal ME structure composition was matched. The characterization of a non-resonant current sensor showed that in the operation range to 5 A, the sensor had a sensitivity of 0.34 V/A, non-linearity less than 1% and for a resonant current sensor in the same operation range, the sensitivity was of 0.53 V/A, non-linearity less than 0.5%.

Bending Modes and Magnetoelectric Effects in Asymmetric Ferromagnetic-Ferroelectric Structure

A model is discussed here for the resonance enhancement of magnetoelectric (ME) interactions in ferrite-piezoelectric bilayers at frequencies corresponding to bending oscillations. The thickness dependence of stress, strain and magnetic and electric fields within the sample are taken into account so that the bending deformations could be considered in an applied magnetic or electric field. The boundary conditions corresponding to bilayers that are free to vibrate at both ends, or simply supported at both ends, or fixed at one end are considered. The explicit expressions for ME voltage coefficients are derived by way of exact solution of electrostatic, magnetostatic and elasto-dynamic equations for thin plate and disk-shaped bilayers. The model is applied to a specific case of nickel and lead zinconate titanate (PZT) bilayer. Theoretical ME voltage coefficients versus frequency and PZT to nickel thickness ratio profiles are in excellent agreement with data.

Loading characteristics of a spin-transfer nano-oscillator

A family of loading and control characteristics of a spin-transfer nano-oscillator (STNO) at various values of direct current have been constructed by integrating the Landau–Lifshitz–Gilbert–Slonczewski equation. The obtained characteristics are compared to approximated dependences calculated using truncated equations with respect to the first harmonic. An approximate expression is derived for the load resistance ensuring the maximum STNO output power.

Magnetoelectric position sensors for automotive application

In this paper it is proposed to use magnetoelectric material as the sensing element of position sensors for car. Proposed ME position sensor has several advantages against the traditional one such as smaller size and weight. Magnetostrictive-piezoelectric layered structure based on PZT and Metglas was used as sensor. The designed sensor showed the peak voltage pulse of about 150 mV. Sensors were tested on a real internal combustion engine of a car.

Voltage-Tunable vapour detector using optical beam shifts in a magneto-electric multilayered structure

We investigate the spatial and angular lateral shifts of a Gaussian light beam reflected from a structure consisting of a nematic liquid crystal cell sandwiched between semi-transparent indium-tin oxide electrodes and deposited on a magneto-electric yttrium-iron garnet film grown on a non-magnetic dielectric gadolinium-gallium garnet substrate. We show that the external voltage applied to the liquid crystal cell allows an efficient tuning of the beam shifts. We propose a scheme for a vapour detection technique based on the measurement of the lateral shift variations induced by tiny changes of the relative permittivity of the air surrounding the system.

Electric and magnetic tuning of the Goos-Hänchen shift of a light beam upon reection from a magneto-electric heterostructure

We investigate theoretically the Goos-Hänchen shift of a Gaussian light beam reflected from a magneto-photonic heterostucture consisting of an electrooptic film, a magneto-electric film, and a nonmagnetic dielectric substrate. We show that the magneto-electric coupling increases up to several times the amplitude of the Goos-Hänchen shift of a p-(s-) polarized incident beam reflected into a s-(p-) polarized beam. Tuning of the magnetization in the magnetic film leads to a nonreciprocal sign change of the lateral shift, and tuning of the shift amplitude can be achieved through a judicious choice of the magnitude and direction of an external dc electric field applied to the system.

Magnetoelectric Effect in Ferrite-Piezoelectric Dual-Phase Structure

This manuscript is devoted to the magnetoelectric coupling in a dimensionally graded magnetostrictive-piezoelectric structure in the electromechanical resonance region. Theoretical frequency dependence of ME voltage coefficient is obtained. Theoretical estimates for the layered structure of lead zirconate-titanate and single-crystal Zn0,3Ni0,7Fe2O4 are in satisfactory agreement with data. The obtained results are expected to facilitate observation of enhanced ME coupling at overlapping of electromechanical and magnetic resonance due to energy transfer between spin waves and phonons.

Magnetic Field Tunable Electromechanical Resonance Properties of Magnetoelectric Bilayer

The present paper focuses on the magnetoelectric coupling in dimensionally graded ferrite-piezoelectric bilayers in the electromechanical resonance region. Using the bilayer as a transducer which converts the ac magnetic field into an ac electric field shows that the transmission coefficient equals approximately -83 dB for zero bias magnetic field and -44 dB for bias field of 340 Oe. Thus, applying the DC field enables one to obtain the transmission coefficient variation range of 39 dB for the investigated structure. The phenomenon is of importance for the realization of multifunctional magnetoelectric devices including sensors and transducers operating at microwave frequencies.