Journal of Physical Studies 17(3), Article 3701 [28 pages] (2013) DOI: https://doi.org/10.30970/jps.17.3701 STUDIES OF FERROICS IN THE ELECTRONIC REGION OF SPECTRUM M. O. Romanyuk1 , B. V. Andrievskyy2, V. Yo. Stadnyk1, O. S. Kushnir3 1Physics Faculty, Ivan Franko Lviv National University, 8, Kyrylo and Mefodiy St., Lviv, UA-79005, Ukraine, 2Faculty of Electronics and Computer Science, Koszalin University of Technology, 2, Sniadeckich St., Koszalin, 75-453, Poland, 3Electronics Faculty, Ivan Franko Lviv National University, 107, Tarnavsky St., Lviv, UA--79005, Ukraine

We describe the studies of well-known ferroics in the region of spectrum that corresponds to their electronic transitions, with the main accent on the newest results and methodical approaches, in particular those based on utilizing contemporary computation techniques.

We describe the studies for the baric changes in refractive indices in the visible spectral range, measurements of the dielectric constant with the ellipsometric methods in the vacuum ultraviolet range using synchrotron radiation, and revealing the temperature dependence of light reflection conditioned by the twinning samples' structure in the region of intrinsic absorption. We calculate the spectra of optical functions in the vacuum ultraviolet range issuing from the first principles, reveal generic origins of different absorption bands, describe baric changes in the electronic polarizability and changes in the structural bonds due to phase transitions. We demonstrate that besides the effects of critical order parameter fluctuations, any consistent description of temperature dependences of different optical properties near the phase transition points based on the Landau theory should include accounting for the point defects of ‟local field” and ‟local temperature” types.

All of these data testify to an important role of the electronic subsystem in ferroics from the viewpoints of both deep fundamental knowledge of the mechanisms of phase transitions and practical applications.

PACS number(s): 78.20 Сі, 78.20 Fm, 77.80.-e, 71.20.Ps, 42.65.An, 42.25.Lc

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