Научная электронная библиотека ULRICH'S Periodicals Directory

Сибирский государственный университет
науки и технологий имени академика М.Ф. Решетнева

Сибирский аэрокосмический журнал
ISSN 2712-8970 (Print) ISSN 2782-5760 (on-line)

Сведения об образовательной организации

UDK 539.22 Doi: 10.31772/2587-6066-2020-21-3-433-440
POINT DEFECTS IN NEMATIC LIQUID CRYSTAL MATERIALS WITH CONICAL ANCHORING AT THE INTERFACE
M. N. Krakhalev, V. F. Shabanov, V. Ya. Zyryanov
Kirensky Institute of Physics, Federal Research Center KSC SB RAS; 50/38, Akademgorodok, Krasnoyarsk, 660036, Russian Federation; Institute of Engineering Physics and Radio Electronics, Siberian Federal University; 79, Svobodny Av., Krasnoyarsk, 660041, Russian Federation; Federal Research Center “Krasnoyarsk Science Center of the Siberian Branch of the Russian Academy of Sciences”; 50, Akademgorodok St., Krasnoyarsk, 660036, Russian Federation
The topological point defects in nematic liquid crystal materials have been studied. The method of oblique light incidence has been proposed to determine an azimuthal director angle of an achiral nematic as well as a chiral nematic (cholesteric). The idea of the method is based on the dependence of the optical phase difference between ordinary and extraordinary light beams on the azimuthal director angle at the layer center at oblique incidence of light on a structure in which the polar director angle of a nematic liquid crystal is not equal to 0° or 90° (conical boundary conditions). It has been shown that the phase difference reaches a maximum at a zero azimuthal angle at the center of the layer regardless of the total twist angle of the director. The developed method has been used to analyze topological defects formed in the nematic and cholesteric layers under conical boundary conditions at the interface. The director field distributions of nematic and cholesteric near the surface point defects (boojums) with topological charges m = +1 and m = –1 have been drawn based on the experimental data. The proposed method of oblique light incidence can be used to analyze a wide class of the achiral and chiral liquid crystal media of various types: smectics, nematics, and cholesterics with tilted or hybrid boundary conditions.
Keywords: topological defect, orientational structure, nematic liquid crystal, optical phase difference.
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Krakhalev Mikhail Nikolaevich – Cand. Sc., senior researcher, Laboratory of molecular spectroscopy, Kirensky
Institute of Physics, Federal Research Center KSC SB RAS, Associate Professor at the Department of General Physics,
Institute of Engineering Physics and Radio Electronics, Siberian Federal University. Е-mail: kmn@iph.krasn.ru.
ShabanovVasilyPhilipovich – Dr. Sc., Professor, Academician, Scientific director of Federal Research Center
"Krasnoyarsk Science Center of the Siberian Branch of the Russian Academy of Sciences". Е-mail:
shabanov@ksc.krasn.ru.
Zyryanov Victor Yakovlevich – Dr. Sc., Professor, Head of the scientific direction and Laboratory of molecular
spectroscopy, Kirensky Institute of Physics, Federal Research Center KSC SB RAS. Е-mail: zyr@iph.krasn.ru.


  POINT DEFECTS IN NEMATIC LIQUID CRYSTAL MATERIALS WITH CONICAL ANCHORING AT THE INTERFACE