Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/4995
Title: Vanishing critical thickness in asymmetric ferroelectric tunnel junctions : first principle simulations
Authors: Cai, Meng-Qiu
Zheng, Yue
Ma, Pui-wai
Woo, Chung-ho
Subjects: Ab initio calculations
Barium compounds
Charge exchange
Density functional theory
Dielectric polarisation
Ferroelectric capacitors
Ferroelectric thin films
Platinum
Strontium compounds
Tunnelling
Issue Date: 15-Jan-2011
Publisher: American Institute of Physics
Source: Journal of applied physics, 15 Jan. 2011, v. 109, no. 2, 024103, p. 1-6.
Abstract: The stability of the remnant polarization in the ferroelectric barrier layer is a prerequisite to applications involving ferroelectric tunnel junctions (FTJs) or capacitors. One of the most important issues in the pursuit of further developments in this area is to overcome the limitations due to the critical thickness, below which the ferroelectric polarization disappears. In this paper we report first-principle density-functional calculations of the charge distribution and polarization in an asymmetric FTJ (A-FTJ), i.e., one with dissimilar electrodes. We found that a significant and stable polarization can be retained down to thicknesses as small as 0.8 nm two unit-cells in a BaTiO₃thin film between Pt and SrRuO₃electrodes, quite unlike the case of symmetric FTJs. We trace this surprising result to the large electric field produced by the charge transfer between the electrodes caused by their different electronic environments, which acts against the depolarization field and enhances the ferroelectricity, leading to the reduction, or even the complete elimination of the depolarization field, leading to the vanishing of the critical thickness. We speculate that this is a general result for A-FTJs, which could be of importance to applications of ferroelectric thin films and tunneling junctions or capacitors where the presence of the critical thickness is a limiting factor.
Rights: © 2011 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in M. Q. Cai et al., J. Appl. Phys. 109, 024103 (2011) and may be found at http://link.aip.org/link/?jap/109/024103.
Type: Journal/Magazine Article
URI: http://hdl.handle.net/10397/4995
DOI: 10.1063/1.3532000
ISSN: 0021-8979 (print)
1089-7550 (online)
Appears in Collections:EIE Journal/Magazine Articles

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