A. V. Golenishchev-Kutuzov

Ordered states of Jahn-Teller distorted MnO6 octahedra in weakly doped lanthanum-strontium manganites

This paper presents the results of investigations of the ordering of Jahn-Teller distorted MnO6 octahedra in lightly doped single crystals of the composition La1 − xSrxMnO3 (0.12 < x < 0.175) using the complex technique including measurements of elastic moduli and damping of high-frequency acoustic waves (700 MHz), electrical conductivity as a function of the temperature (100–400 K), and magnetic field (H ≤ 1.5 T). The self-organization of the orbital, magnetic, and Jahn-Teller orderings and their influence on the transport, magnetic, and structural properties of lightly doped manganites have been investigated based on the analysis of the experimental results. The decisive influence of the local and cooperative Jahn-Teller orderings on the colossal magnetoresistance effect has been established.

Photoinduced decrease in local polarization switching fields in lithium niobate crystals

Variations in local polarization switching fields EC in lithium niobate crystals have been investigated under laser irradiation of the z surface. It has been established that the simultaneous application of an electric field in the direction opposite to the spontaneous polarization field and laser beam leads to a decrease in the field EC.

Acoustic anomalies near phase transitions in manganite

The behavior of the velocities and attenuation of ultrasonic waves propagating in La1−xSrxMnO3 (x=0.175) manganite at frequencies of 700–800 MHz is studied in the temperature interval from 320 to 180 K, and the effect of magnetic field on the acoustic parameters is investigated. The transformation of acoustic modes in the vicinity of the magnetic phase transition is observed. The changes in the acoustic parameters near the structural and magnetic phase transitions are shown to be related to the strong spin-phonon and electron-phonon interactions.

Dynamics of photo-induced changes in the elastic characteristics of lithium niobate crystals doped with Jahn–Teller Fe2+ ions

The effect of admixture Jahn–Teller Fe2+ ions on the elastic characteristics of lithium niobate was studied. The appearance of photostrains and a change in elastic moduli under the influence of laser radiation was established, thus enabling the creation of device elements with optically controlled elastic characteristics.

Contribution from structural Jahn–Teller ions to the elastic and ferroelectric properties of lithium niobate and lithium tantalate

Elastic and ferroelectric characteristics of single crystals of lithium niobate and tantalate are investigated in a wide range of temperatures by complex acoustooptic means. The contribution from Jahn–Teller NbO6 and TaO6 systems to the characteristics of elastic moduli, ultrasonic attenuation, and nonlinear optical coefficients is analyzed using a new phenomenological model. It is hypothesized that the displacement of Nb5+ and Ta5+ ions, which exhibit the second-order Jahn–Teller effect along trigonal axis C, and the subsequent ordering of octahedral, result in unusual elastic and ferroelectric properties.

Two-dimensional photonic and phononic crystals based on lithium niobate

Specific features of the preparation and application of photonic and phononic crystals containing two-dimensional periodic domain structures are considered. Particular attention is given to the formation of two-dimensional periodic domain structures in oxide ferroelectrics using strongly focused laser beams. Specific features of the nonlinear properties of such two-dimensional structures during the propagation of optical and acoustic beams through them are described.

Effect of impurity iron ions on the formation of photoinduced lattices and domain structures in lithium niobate

Processes and mechanisms of the formation of lattices and periodic domain structures in iron-doped lithium niobate monocrystals under the effect of laser beams are examined. The role of Jahn-Teller Fe2+ ions in the formation of photoinduced periodic structures is demonstrated.

Photon-phonon interaction on periodic structures

Features of the interaction between optical and acoustical waves with the same wavelength and multiple of the structural layer period, propagating simultaneously through periodic structures, are analyzed. The current state of and prospects for photon-phonon crystals being used for amplification, the generation of gigahertz acoustic waves, and other nonlinear optical and acoustic effects are examined.

Formation of submicron partially ordered domain structures in ferroelectric and magnetic materials

Formation of domains and partially ordered periodic domain structures in ferroelectric and magnetic oxides of metals of transition groups has been investigated. Physical features of appearance of submicron periodic domain structures and possibilities of their use for the control over the parameters of high-frequency acoustic waves have been considered using the example of single crystals of lithium niobate and lanthanum-strontium manganites.

Ferroelectric and magnetic media with nanoscale regular domain structures

The formation and physical characteristics of irregular nano- and microscale domain structures were studied in ferroelectric and magnetic perovskite metal oxides. Their nonlinear optical, magnetic and elastic characteristics were established. The prospects for their application in the frequency and mode transformation of optical and acoustic waves are examined.