Dielectric properties of ferroelectric lithium tantalate crystals studied by terahertz time-domain spectroscopy

被引：0

作者：

Kojima, Seiji ^{[1
]}

Kitahara, Hideaki ^{[2
]}

Nishizawa, Seizi ^{[3
]}

Wada Takeda, Mitsuo ^{[1
]}

机构：

[1] Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan

[2] Department of Physics, Faculty of Science, Shinshu University, Matsumoto, Nagano 390-8621, Japan

[3] Res. Ctr. Dev. Far-Infrared Region, Fukui University, Fukui 910-8507, Japan

来源：

| 2003年 / Japan Society of Applied Physics卷 / 42期

关键词：

Ferroelectric materials - Oscillators (electronic) - Permittivity - Phonons - Spectroscopy;

D O I：

10.1143/jjap.42.6238

中图分类号：

学科分类号：

摘要：

The terahertz (THz) dynamics of ferroelectric lithium tantalate crystals has been investigated using the latest THz time-domain spectroscopy. The intensity and phase shift of transmitted THz radiation have been accurately measured for the propagation of the THz radiation along the y-axis down to 3 cm-1 (0.1 THz). The phonon-polariton dispersion relations have been determined from the phase shift for A1(z) and E(x,y) symmetry polaritons. The dispersion relations of both symmetries show no avoided crossing below 60 cm-1 (1.8 THz). The complex dielectric constants Εz(ω) and Εx(ω) in the sub-THz to THz regions have also been determined as functions of frequency. Both the real and imaginary parts of Εx(ω) are well reproduced using a single damped harmonic oscillator model. However, those of Εz(ω) indicate the excess part, which may be attributed to a relaxation process related to the order-disorder nature of ferroelectricity.

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