Condensed Matter, abstract
cond-mat/0304196
From: David Vanderbilt <dhv@physics.rutgers.edu>
Date: Tue, 8 Apr 2003 15:31:55 GMT (17kb)
Extrinsic models for the dielectric response of CaCu{3}Ti{4}O{12}
Authors:
Morrel H. Cohen,
J. B. Neaton,
Lixin He,
David Vanderbilt (Department of Physics and Astronomy, Rutgers University)
Comments: 9 pages, with 1 postscript figure embedded. Uses REVTEX and epsf
macros. Also available at
this http URL
Subj-class: Materials Science
The large, temperature-independent, low-frequency dielectric constant
recently observed in single-crystal CaCu{3}Ti{4}O{12} is most plausibly
interpreted as arising from spatial inhomogenities of its local dielectric
response. Probable sources of inhomogeneity are the various domain boundaries
endemic in such materials: twin, Ca-ordering, and antiphase boundaries. The
material in and neighboring such boundaries can be insulating or conducting. We
construct a decision tree for the resulting six possible morphologies, and
derive or present expressions for the dielectric constant for models of each
morphology. We conclude that all six morphologies can yield dielectric behavior
consistent with observations and suggest further experiments to distinguish
among them.