V. M. Laletin

Frequency and field dependence of magnetoelectric interactions in layered ferromagnetic transition metal-piezoelectric lead zirconate titanate

The strength of magnetoelectric (ME) coupling at 10Hz–3MHz has been measured in trilayers of Fe, Co, or Ni and lead zirconate titanate (PZT). The strongest ME coupling is measured for trilayers with Ni and the weakest in Co. Data on ME voltage coefficient αE versus bias magnetic field H for Fe–PZT–Fe show unique features including zero crossing and sign reversal. Measurements of frequency dependence of αE reveal a giant ME coupling due to the electromechanical resonance at 200–300kHz for radial modes and at ∼2.7MHz for thickness modes. Theoretical estimates of field and frequency dependence of αE are in very good agreement with the data.

Giant magnetoelectric effect in composite materials in the region of electromechanical resonance

The magnetoelectric effect in multilayer ferrite-piezoelectric composites has been theoretically and experimentally studied. Using the method of effective parameters, an expression for the magnetoelectric coefficient is determined and its frequency dependence is analyzed. It is shown that, in the region of electromechanical resonance, the magnitude of the effect exceeds a low-frequency value by more than an order of magnitude. The results of calculations obtained for a nickel ferrite spinel-PZT composite are in good agreement with the experimental data.

Resonant amplification of the magnetoelectric effect in ferrite-piezoelectric composites

The magnetoelectric effect in ferrite-piezoelectric composites is considered. A theory of the magnetoelectric effect in the electromechanical-resonance region for disk-shaped samples is presented. The magnetooptical coefficient is calculated for longitudinal and transverse orientations of electric and magnetic fields. It is shown that the effect increases by a few orders of magnitude at the electromechanical-resonance frequency. The frequency dependence of the effect is experimentally studied for a ferrite-nickel spinel-PZT composite. A resonant increase in the effect is observed (in agreement with the theory); the highest value of the magnetoelectric coefficient was 15 V/(cm Oe).

Low-frequency and resonance magnetoelectric effects in nickel ferrite-PZT bulk composites

The direct and inverse magnetoelectric effects in nickel ferrite spinel-PZT bulk composites are experimentally studied at low frequencies and in the range of electromechanical resonance. The frequency and field dependences of the magnetoelectric effect are analyzed. It is shown that the direct effect resonantly grows at the antiresonance frequency and the inverse effect grows at the resonance frequency. The dependences of the resonance and antiresonance frequencies on the composition of the composite material are determined.

Magnetoelectric effect in a magnetostrictive-piezoelectric bilayer structure

The results of theoretical and experimental investigations of the magnetoelectric effect in a magnetostrictive-piezoelectric bilayer structure have been presented. The expression for the magnetoelectric voltage coefficient in the region of electromechanical resonance has been derived based on the joint solution of the equations of motion for the magnetostrictive and piezoelectric media and the constitutive relations. The dependence of the magnitude of the effect on the thickness of the ferrite and piezoelectric layers has been analyzed. The experimental results for nickel-lead zirconate-titanate bilayer structures have been reported. The theoretical results agree perfectly with the experimental data.

Inverse magnetoelectric effect in disk-shaped samples of ferrite piezoelectric composites

A theory of the inverse magnetoelectric effect in the vicinity of electromechanical resonance in disk-shaped samples is presented. An expression for the coefficient of the inverse magnetoelectric transformation has been obtained using the effective parameter method. It has been shown that a sharp increase in the magnitude of the effect occurs at a frequency of electromechanical resonance, and the resonance frequencies for the direct and inverse magnetoelectric effects are different. The dependences of the resonance frequencies on the ferrite percentage in ferrite-nickel spinel samples and lead zirconate titanate samples have been studied experimentally.

Frequency dependence of the magnetoelectric effect in ceramic composites based on lead zirconate titanate and nickel ferrite

The magnetoelectric (ME) effect in ferrite-piezoelectric ceramic composites based on a nickel ferrite spinel and lead zirconate titanate (PZT) has been theoretically and experimentally studied. Using the method of effective medium, an expression for the ME coefficient is obtained and its frequency dependence is analyzed. It is shown that, in the region of electromechanical resonance, the magnitude of the ME effect exceeds that in a layered structure of the same components and is more than two orders of magnitude greater than the low-frequency value. The results of calculations for a nickel ferrite spinel-PZT composite are in good agreement with the experimental data.

The nonlinear resonance magnetoelectric effect in magnetostrictive-piezoelectric structures

We have studied a magnetoelectric (ME) effect that is nonlinear with respect to the alternating magnetic field. It is established that resonance excitation of an alternating electric field takes place in magnetostrictive-piezoelectric bilayer structures under the action of alternating magnetic field at a frequency that is half as small as the electromechanical resonance frequency. The nonlinear ME effect, in contrast to the linear one, does not depend on the constant (magnetizing) bias field and is quadratic with respect to the alternating magnetic field.

Voltage transformer based on inverse magnetoelectric effect

A voltage transformer, the operation of which is based on the inverse magnetoelectric effect, has been studied. The device comprises a nickel-PZT-nickel trilayer capacitor structure on which an induction coil is wound. It is established that the frequency dependence of the output signal has a resonance character and the transmission characteristic is linear in a broad range of input voltages.

Nonlinear magnetoelectric effect in composite multiferroics

The theoretical and experimental studies of the nonlinear magnetoelectric effect in composite multiferroics in the low-frequency spectral region and in the electromechanical resonance region have been performed. It has been shown that such structures demonstrate a nonlinear magnetoelectric effect, which is quadratic in ac magnetic field strength at weak magnetic fields. In the region of the electromechanical resonance, the resonance excitation of an electric field occurs by means of ac magnetic field at a frequency lower than the resonance frequency by a factor of two. In the low-frequency spectral region, there is a difference of amplitude values of two neighboring voltage maxima due to the superposition of signals from the linear and nonlinear effects, and the difference is proportional to the dc magnetic field strength in weak fields. The results of the experimental study of the two-layer permendur-lead zirconate titanate structure are presented.