TY - Generic T1 - Finite size effects in ferroelectric nanosystems: Absence of mode softening T2 - 2003 Nanotechnology Conference and Trade Show - Nanotech Y1 - 2003 A1 - D. Wolpert A1 - W. Cox A1 - J. Cerne A1 - A. Markelz A1 - T. Zhao A1 - R. Ramesh ED - Romanowicz M. KW - Ferroelectric materials KW - Fourier Transform Infrared Spectroscopy KW - Frequency ranges KW - Lead compounds KW - Mode softening KW - nanostructured materials KW - Natural frequencies KW - Optical modes KW - Permittivity KW - phase transitions KW - phonons KW - Routers KW - Thermal effects AB -

We present measurements of the mode softening behavior for PbZr 0.5Ti0.5O3 (PZT(50)) thin films using terahertz time domain spectroscopy (TTDS). The films were grown using pulsed laser deposition (PLD) techniques on silicon substrates to study how reduced size affects the mode softening behavior. At room temperature two modes are observed at 1.1 THz (37 cm-1) and at 2.3 THz (77 cm-1). As the temperature is increased toward Tc we do not see strong mode softening, but rather a spectral weight transfer from the high frequency mode to the low frequency mode. This absence of mode softening is more dramatic than that reported by other investigators[1]. We will discuss the possible sources for this discrepancy. These results suggest a change in lattice dynamics for nanoscale ferroelectric films that may be highly dependent on the sample preparation technique.

JF - 2003 Nanotechnology Conference and Trade Show - Nanotech CY - San Francisco, CA VL - 2 SN - 0972842209 N1 - cited By 0 ER -