Nonlinear optical studies of the temperature evolution of local asymmetric regions in solid solutions (1-x) PbMg_1/3Nb_2/3O₃-xPbSc_1/2Nb_1/2O₃

Abstract

The temperature dependencies of second harmonic generation (SHG) in (1-x)PMN–xPSN solid solutions (x = 1, 0.35, 0.23, 0.1, 0) are measured. Presence of SHG signal in centrosymmetric phase in all samples studied is demonstrated. It indicates asymmetric regions in the centrosymmetric phase. In PMN crystal (x = 0) in the centrosymmetric phase, SHG temperature dependence follows deviations of strain and refractive index from their high-temperature dependencies, which are determined by random electric fields in local polar regions. In the intermediate temperature range, where macroscopic spontaneous polarization disappears, SHG signal is caused by relatively large and long-lived polar asymmetric regions.

Keywords:

• (1-x)PMN–xPSN solid solution
• nonlinear regions
• phase transition
• second harmonic generation

Acknowledgments

Some part of the experiments was performed in the multiple-access center “High-Resolution Spectroscopy of Gases and Condensed Matter” in IA&E SB RAS (Novosibirsk, Russia) and in Ural Center for Shared Use “Modern Nanotechnology” Ural Federal University (Reg. № 2968).

Additional information

Funding

This work was supported by the Russian Foundation for Basic Research (projects No. 20-42-54002 and 19-42-543-016), Government of Novosibirsk region (No. 20-42-54002 and 19-42-543-016), and State assignment Basic Project of IA&E SB RAS (No. 121032400052-6).