Yoshihiro Ishibashi

Abstract: The dielectric spectra of thiourea and BaMnF4 were determined in all phases (85-300 K) in the 3-30 cm-1 region using the monochromatic spectrometer with tunable oscillator. Moreover, far infrared (30-450 cm-1) reflectivity of BaMnF4 at 90 and 300 K was measured and evaluated to obtain the dielectric spectra. In the case of thiourea a new extra mode near 7 cm-1 was observed in the paraelectric region. A rather complex dielectric dispersion was found in incommensurate phases in qualitative accord with theoretical expectations. In the case of BaMnF4, two low-frequency modes which partially soften at Tc were found in agreement with recent Raman results.

TL;DR: In this article, the temperature dependence of the third-order nonlinear susceptibility ϵ3 in relaxor ferroelectrics (1-x)Pb(Zn1/3Nb2/3)O3-8%PbTiO3 was measured in the vicinity of critical endpoint, TCEP (172°C).

TL;DR: In this paper, the p-E hysteresis loop with a square shape and a small coercive field was reproduced on the basis of the Landau theory with the anisotropy parameter γ 2.

TL;DR: In this paper, the coercive fields were discussed from the viewpoint of the relaxor states resulting from random fields based on lattice defects due to Bi ions and oxygen vacancies, and the microscopic remarkable difference of domain switching depends on the coercive field caused by localized nucleation of domains with reversed polarization.

TL;DR: In this paper, the growth of the cholesteric finger pattern appeared in a large pitch-cholesteric liquid crystal has been numerically investigated and the time evolution of the director field is calculated from a motion of equation constructed from the Frank elastic free energy density.