@article{10902/4238,
year = {2006},
month = {9},
url = {http://hdl.handle.net/10902/4238},
abstract = {Scaling of the structural order parameter, polarization, and electrical properties was investigated in model ultrathin epitaxial SrRuO3/PbZr0.2Ti0.8O3/SrRuO3/SrTiO3 heterostructures. High-resolution transmission electron microscopy images revealed the interfaces to be sharp and fully coherent. Synchrotron x-ray studies show that a high tetragonality (c/a∼1.058) is maintained down to 50Å thick films, suggesting indirectly that ferroelectricity is fully preserved at such small thicknesses. However, measurement of the switchable polarization (ΔP) using a pulsed probe setup and the out-of-plane piezoelectric response (d33) revealed a systematic drop from ∼140μC/cm2 and 60pm/V for a 150Å thick film to 11μC/cm2 and 7pm/V for a 50Å thick film. This apparent contradiction between the structural measurements and the measured switchable polarization is explained by an increasing presence of a strong depolarization field, which creates a pinned 180° polydomain state for the thinnest films. Existence of a polydomain state is demonstrated by piezoresponse force microscopy images of the ultrathin films. These results suggest that the limit for a ferroelectric memory device may be much larger than the fundamental limit for ferroelectricity.},
publisher = {American Institute of Physics},
publisher = {Journal of Applied Physics, vol. 100, iss. 5, art. num.  051609 (2006)},
title = {Scaling of structure and electrical properties in ultrathin epitaxial ferroelectric heterostructures},
author = {Nagarajan, Valanoor and Junquera Quintana, Francisco Javier and He, Jiaqing and Jia, Chunlin and Waser, Rainer M. and Lee, KyoungIl and Kim, Youngkeun and Baik, Sunggi and Zhao, Tong and Ramesh, Ramamoorthy and Ghosez, Philippe and Rabe, Karin M.},
}