01941nas a2200373   4500008004100000020001500041245008000056210006900136260003100205300001000236490000600246520087600252653002801128653004401156653002101200653001901221653001901240653002901259653002401288653001801312653001701330653002201347653001201369653001201381653002001393100001601413700001201429700001401441700001601455700001301471700001501484700001901499856004901518       2003                        eng d  a097284220900aFinite size effects in ferroelectric nanosystems: Absence of mode softening0 aFinite size effects in ferroelectric nanosystems Absence of mode  aSan Francisco, CAc02/2003  a76-810 v23 a<p>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.</p>10aFerroelectric materials10aFourier Transform Infrared Spectroscopy10aFrequency ranges10aLead compounds10aMode softening10ananostructured materials10aNatural frequencies10aOptical modes10aPermittivity10aphase transitions10aphonons10aRouters10aThermal effects1 aWolpert, D.1 aCox, W.1 aCerne, J.1 aMarkelz, A.1 aZhao, T.1 aRamesh, R.1 aM., Romanowicz  uhttps://markelz.physics.buffalo.edu/node/275