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Journal ArticleDOI

Ferroelectric polarization-leakage current relation in high quality epitaxial Pb ( Zr , Ti ) O 3 films

Lucian Pintilie1, Ionela Vrejoiu1, Dietrich Hesse1, G. LeRhun1, Marin Alexe1 
08 Mar 2007-Physical Review B (American Physical Society)-Vol. 75, Iss: 10, pp 104103
TL;DR: Stolichnov et al. as discussed by the authors showed that the voltage behavior of the leakage current has a minor dependence on thickness, which rules out the space-charge limited currents as main leakage source.
Abstract: Leakage current measurements were performed on epitaxial, single-crystal quality $\mathrm{Pb}(\mathrm{Zr},\mathrm{Ti}){\mathrm{O}}_{3}$ films with thicknesses in the $50--300\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ range. It was found that the voltage behavior of the leakage current has a minor dependence on thickness, which rules out the space-charge limited currents as main leakage source. Temperature-dependent measurements were performed to obtain more information on the transport mechanism through the metal-ferroelectric-metal (MFM) structure. The results are analyzed in the frame of interface-controlled Schottky emission. A surprisingly low value of only $0.12--0.13\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ was obtained for the potential barrier, which is much smaller than the reported value of $0.87\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ [I. Stolichnov et al., Appl. Phys. Lett. 75, 1790 (1999)]. The result is explained by the effect of the ferroelectric polarization on the potential barrier height. The low value of the effective Richardson constant, of the order of ${10}^{\ensuremath{-}7}--{10}^{\ensuremath{-}6}\phantom{\rule{0.3em}{0ex}}\mathrm{A}∕{\mathrm{cm}}^{2}\phantom{\rule{0.2em}{0ex}}{\mathrm{K}}^{2}$, suggests that the pure thermionic emission is not the adequate conduction mechanism for epitaxial MFM structures. The true mechanism might be interface-controlled injection, followed by a low mobility drift through the film volume.
Citations
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Journal ArticleDOI
TL;DR: The rich physics of the hexagonal system with a truly semiconducting bandgap where structural trimerization, ferroelectricity, magnetism and charge conduction are intricately coupled are revealed.
Abstract: Hexagonal YMnO(3) shows a unique improper ferroelectricity induced by structural trimerization. Extensive research on this system is primarily due to its candidacy for ferroelectric memory as well as the intriguing coexistence of ferroelectricity and magnetism. Despite this research, the true ferroelectric domain structure and its relationship with structural domains have never been revealed. Using transmission electron microscopy and conductive atomic force microscopy, we observed an intriguing conductive 'cloverleaf' pattern of six domains emerging from one point--all distinctly characterized by polarization orientation and structural antiphase relationships. In addition, we discovered that the ferroelectric domain walls and structural antiphase boundaries are mutually locked and this strong locking results in incomplete poling even when large electric fields are applied. Furthermore, the locked walls are found to be insulating, which seems consistent with the surprising result that the ferroelectric state is more conducting than the paraelectric state. These fascinating results reveal the rich physics of the hexagonal system with a truly semiconducting bandgap where structural trimerization, ferroelectricity, magnetism and charge conduction are intricately coupled.

421 citations


Cites background from "Ferroelectric polarization-leakage ..."

  • ...The polarization-orientation dependence of conduction, especially at low voltages, may be understood in terms of the Schottky barrier at a metallic-tip-semiconductor rectifying junctio...

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Journal ArticleDOI
TL;DR: It is shown that owing to the coupling between magnetization and ferro electric polarization at the interface between the electrode and barrier of a multiferroic tunnel junction, the spin polarization of the tunnelling electrons can be reversibly and remanently inverted by switching the ferroelectric polarization ofThe barrier.
Abstract: Spin-polarized transport in ferromagnetic tunnel junctions, characterized by tunnel magnetoresistance, has already been proven to have great potential for application in the field of spintronics and in magnetic random access memories. Until recently, in such a junction the insulating barrier played only a passive role, namely to facilitate electron tunnelling between the ferromagnetic electrodes. However, new possibilities emerged when ferroelectric materials were used for the insulating barrier, as these possess a permanent dielectric polarization switchable between two stable states. Adding to the two different magnetization alignments of the electrode, four non-volatile states are therefore possible in such multiferroic tunnel junctions. Here, we show that owing to the coupling between magnetization and ferroelectric polarization at the interface between the electrode and barrier of a multiferroic tunnel junction, the spin polarization of the tunnelling electrons can be reversibly and remanently inverted by switching the ferroelectric polarization of the barrier. Selecting the spin direction of the tunnelling electrons by short electric pulses in the nanosecond range rather than by an applied magnetic field enables new possibilities for spin control in spintronic devices.

409 citations

Journal ArticleDOI
TL;DR: A ferroelectric-resistive random access memory consisting of a conductive BiFeO3 epitaxial thin film with a unipolar diode current modulated by electric polarization orientation is reported.
Abstract: A ferroelectric-resistive random access memory consisting of a conductive BiFeO3 epitaxial thin film with a unipolar diode current modulated by electric polarization orientation is reported. This device has a memory that lasts for months, a sufficiently high on current and on/ off ratio to permit ordinary sense amplifiers to measure "1" or " 0", and is fully compatible with complementary metal- oxide semiconductor processing.

386 citations

Journal ArticleDOI
TL;DR: The main drawback of this intriguing effect is that only a tiny photocurrent is generated in typical large-bandgap and highly-insulating ferroelectric materials such as LiNbO 3.
Abstract: IO N The ferroelectric photovoltaic (FPV) effect—a photocurrent is created in ferroelectric materials by ultraviolet (UV) light illumination and its direction depends upon ferroelectric polarization—has received considerable attention as a promising alternative to conventional photonic and photovoltaic devices. However, the main drawback of this intriguing effect is that only a tiny photocurrent is generated in typical large-bandgap and highly-insulating ferroelectric materials such as LiNbO 3 . [ 1 , 2 ]

360 citations

Journal ArticleDOI
TL;DR: The domain wall conduction, nonlinear and highly asymmetric due to the specific local probe measurement geometry, shows thermal activation at high temperatures, and high stability over time.
Abstract: Domain wall conduction in insulating Pb(Zr(0.2) Ti(0.8))O(3) thin films is demonstrated. The observed electrical conduction currents can be clearly differentiated from displacement currents associated with ferroelectric polarization switching. The domain wall conduction, nonlinear and highly asymmetric due to the specific local probe measurement geometry, shows thermal activation at high temperatures, and high stability over time.

322 citations

References
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Proceedings Article
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Journal ArticleDOI
TL;DR: In this article, the authors introduce the current state of development in the application of ferroelectric thin films for electronic devices and discuss the physics relevant for the performance and failure of these devices.
Abstract: This review covers important advances in recent years in the physics of thin-film ferroelectric oxides, the strongest emphasis being on those aspects particular to ferroelectrics in thin-film form. The authors introduce the current state of development in the application of ferroelectric thin films for electronic devices and discuss the physics relevant for the performance and failure of these devices. Following this the review covers the enormous progress that has been made in the first-principles computational approach to understanding ferroelectrics. The authors then discuss in detail the important role that strain plays in determining the properties of epitaxial thin ferroelectric films. Finally, this review ends with a look at the emerging possibilities for nanoscale ferroelectrics, with particular emphasis on ferroelectrics in nonconventional nanoscale geometries.

1,908 citations

Journal ArticleDOI
TL;DR: It is shown that the polarization as defined above also has a direct and predictive relationship to the surface charge which accumulates at an insulating surface or interface.
Abstract: A definition of the electric polarization of an insulating crystalline solid is given in terms of the centers of charge of the Wannier functions of the occupied bands The change of this quantity under an adiabatic evolution of the Hamiltonian has previously been shown to correspond to the physical change in polarization Here, we show that the polarization as defined above also has a direct and predictive relationship to the surface charge which accumulates at an insulating surface or interface

963 citations

BookDOI
01 Jan 1979

593 citations