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Description
Control of the ordered systems properties can be effectively implemented through deformations formed by various external influences, for example, electric fields, laser radiation or their combination. In a number of cases, crystals are sensitive to both types of influences, which, on the one hand, makes them promising materials within straintronics purposes, and, on the other hand, complicates their study due to the simultaneous activation of a complex of deformation processes. Highly informative X-ray diffraction methods can become the basis for a complex technique that would allow in-situ study physical properties of promising crystalline materials that are sensitive to both optical and electrical influences, as well as separate their contributions to the overall deformation pattern.
In this work, a complex technique for studying electrophysical properties and photovoltaic processes in functional crystals based on X-ray diffractometry methods is introduced. After initial estimation of the X-ray diffraction parameters of the sample, an algorithm of the techniques implies a series of measurements are sequentially carried out under conditions of separate and simultaneous exposure of an external electric field and laser radiation. X-ray diffraction measurements in double- and triple-crystal schemes allow one to separate deformation components of tension/compression and twisting. The time-resolved X-ray diffraction technique based on synchronization of the measuring equipment with the system of electrical and optical excitation of the sample using to record fast deformation dynamics. Finally, measurements with complementary methods are conducted, particularly, registration of electrophysical characteristics and sample temperature during an experiment, which make possible numerical estimation of the electrical and thermal components of deformation processes contribution respectively.
Approbation of the proposed technique in case of a photo- and electroactive Fe:LiNbO3 (Fe 0.02%) single crystal made it possible to separate the contributions of thermal expansion, pyroelectric and piezophotovoltaic effects to the overall deformation pattern, and also determine their amplitudes and formation times. Such results demonstrate high efficiency of the technique, which opens up prospects for creation of a new generation of sensors, energy-saving computing devices and information storage systems.
This work was supported by the Ministry of Science and Higher Education within the State Assignment of the Federal Research Center “Crystallography and Photonics” of the Russian Academy of Sciences and within the framework of grant No. 075-15-2021-1362.