Condensed Matter, abstract
cond-mat/0306205
From: David Vanderbilt <dhv@physics.rutgers.edu>
Date: Mon, 9 Jun 2003 01:43:22 GMT (36kb)
Anomalous enhancement of tetragonality in PbTiO3 induced by negative
pressure
Authors:
Silvia Tinte,
Karin M. Rabe,
David Vanderbilt (Department of Physics and Astronomy, Rutgers University)
Comments: 9 pages, with 9 postscript figures embedded. Uses REVTEX and epsf
macros. Also available at
this http URL
Subj-class: Materials Science
Using a first-principles approach based on density-functional theory, we find
that a large tetragonal strain can be induced in PbTiO3 by application of a
negative hydrostatic pressure. The structural parameters and the dielectric and
dynamical properties are found to change abruptly near a crossover pressure,
displaying a ``kinky'' behavior suggestive of proximity to a phase transition.
Analogous calculations for BaTiO3 show that the same effect is also present
there, but at much higher negative pressure. We investigate this unexpected
behavior of PbTiO3 and discuss an interpretation involving a phenomenological
description in terms of a reduced set of relevant degrees of freedom.