Terahertz Response of Ferroelectric Nanofibers
by Tian, Z.; Xin, K.; Wang, M. W.; Han, J. G.; Wang, H. Z.; Tian, Z. R.; Zhang, W. L.
Far-infrared optical and dielectric properties of ferroelectric SrTiO(3) and BaTiO(3) nanofibers, prepared by hydrothermal syntheses, were studied using terahertz time-domain spectroscopy. The power absorption, refractive index, and complex dielectric function were characterized in the frequency range from 0.2 to 1.0 THz. The measured results are well reproduced by theoretical fittings based on the dielectric models and the effective medium model. The study reveals that the low-frequency dielectric properties of the ferroelectric SrTiO(3) nanofibers are associated with the lowest transverse optical (TO) soft mode TO1 at 2.70 THz (90.0 cm(-1)), and that of the ferroelectric BaTiO(3) nanofibers are related to the lowest pair of transverse optical (TO) and longitudinal optical (LO) modes near 5.35 THz, which are both consistent with their bulk single-crystal and thin-film counterparts.