### Session Y22: Ferroelectric and Structural Phase Transitions

8:00 AM–11:00 AM, Friday, March 25, 2011
Room: D163

Chair: Jason Lashley, Los Alamos National Laboratory

Abstract ID: BAPS.2011.MAR.Y22.4

### Abstract: Y22.00004 : Ferroelectricity in CaTiO$_{3}$ Single Crystal Surfaces and Thin Films and Probed by Nonlinear Optics and Raman Spectroscopy

8:36 AM–8:48 AM

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#### Authors:

Eftihia Vlahos
(The Pennsylvania State University)

Tom Lummen
(The Pennsylvania State University)

Ryan Haislmaier
(The Pennsylvania State University)

Sava Denev
(The Pennsylvania State University)

Charles Brooks
(The Pennsylvania State University)

Michael Biegalski
(Oak Ridge National Lab)

Darrell Schlom
(Cornell University)

Carl-Johan Eklund
(Rutgers University)

Karin Rabe
(Rutgers University)

Craig Fennie
(Cornell University)

Venkatraman Gopalan
(The Pennsylvania State University)

Bulk CaTiO$_{3}$ has a centrosymmetric point group and is \textit{not }polar or ferroelectric. However, we present surprising results that show highly regular polar domains in single crystals of CaTiO$_{3}$. Confocal Second Harmonic Generation (SHG) and Raman imaging studies were carried out on perovskite CaTiO$_{3}$ crystal surfaces. They reveal large, crystallographic polar domains at room temperature, with in-plane polarization components delineated by twin walls. SHG analysis indicates that the highest symmetry of the polar surface is $m$(space group P$c)$ with polarization in the $m$ plane. In addition, we present results of the polar domain structure imaged before and after the application of an external electric field. Finally, we present the SHG studies of CaTiO$_{3}$ thin films grown using reactive Molecular Beam Epitaxy (MBE); these films are predicted by theory to be ferroelectric and are shown experimentally, both with SHG and in-plane dielectric measurements, to be ferroelectric for temperatures less than $\sim$150 K with group symmetry \textit{mm}2.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.MAR.Y22.4