Publications by Alexander Tagantsev

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A comprehensive study of: leakage conduction in Pb(ZrxTi1-x)O-3 films with Pt electrodes is carried out. The conduction properties of films prepared in different ways (sol-gel coating, metalorganic chemical vapor deposition, sputtering) were studied by using different experimental techniques including variation of the applied voltage profile, photoassisted measurements, measurements at elevated temperatures, and variation of the prehistory of the samples. Based on the collective data, it is concluded that t

The switching kinetics in ferroelectric thin films has been intensively studied during the past decade. It is widely accepted that this kinetics is basically governed by the dynamics of domain coalescence (the Kolmogorov-Avrami-Ishibashi model). This conclusion is mainly supported by fitting the time dependence of the switching currents to that predicted by this model, the fit being typically performed in a 1-2 decade interval of time. The present paper reports on a study of the switching kinetics in modifi

The region-by-region polarization switching in ferroelectric Pb(Zr,Ti)O-3 thin films sandwiched between Pt electrodes has been directly observed using piezoelectric scanning probe microscopy. A resolution improved by one order-of-magnitude compared to the ...

Understanding of polarization reversal mechanisms in ferroelectric films is essential for evaluation and prediction of the properties of ferroelectric devices including nonvolatile memories. The widely accepted approach based on the domain wall motion kinetics describes correctly switching in single crystals but does not work properly for thin ferroelectric films used for memory applications. Recently an alternative approach based the on statistics of nucleation of the reversed polarization domain has been

Flexoelectric effect is the response of electric polarization to the mechanical strain gradient. At the nano-scale, where large strain gradients are expected, the flexoelectric effect becomes appreciable and may substitute piezoelectric effect in centrosym ...

Polarization reversal in BiFeO3 (BFO) thin films in a parallel-plate capacitor configuration has been explored using piezo-force microscopy (PFM). Through-electrode mapping of the local piezoresponse allows for direct observation of the domain growth, whic ...

Relaxor Pb(Sc-12/Ta-1/2)O-3 (PST) thin films have been prepared using mixed alkoxide and acetate precursors on TiO2/Pt/TiO2/SiO2/Si substrates. Relaxor behavior as evidenced by frequency dispersion of the permittivity as a function of temperature was observed, as well as a thickness dependence of the dielectric constant. The highest values of dielectric constant were observed for the thicker 650 nm samples displaying a room temperature dielectric constant near 2000, with a loss tangent of 0.3% at 1 kHz. The

This paper addresses the problem of time-dependent dielectric breakdown of Pb(Zr,Ti)O-3 (PZT) thin films. It is shown by using constant-current breakdown measurements, that for PZT film capacitors with Pt and SrRuO3 (SRO) electrodes the breakdown onset is controlled by charge to breakdown (Q(BR)) rather than the voltage applied to the capacitor. The QBR value for the asymmetrical Pt/SrRuO3/PZT/Pt capacitors is found to be much higher that for the Pt/PZT/Pt system. Polarization fatigue caused by bipolar volt

The non-linear dielectric properties of single crystals of PbMg1/3Nb2/3O3 relaxer ferroelectric were investigated experimentally by using measurements of the dielectric permittivity of this material as a function of the DC bias and the AC driving fields. The results were analyzed using four models of the dielectric response of relaxors currently discussed in the literature, It was shown that among them only one model was consistent with the experimental data. This provides strong evidence that the mechanism

The charged domain wall is an ultrathin (typically nanosized) interface between two domains; it carries bound charge owing to a change of normal component of spontaneous polarization on crossing the wall. In contrast to hetero-interfaces between different ...

A simple and reliable method which allows one to distinguish between the two major microscopic scenarios for the suppression of the switching polarization (P-r(s)), i.e., pinning of ferroelectric domain walls (DWs) through the Pb(Zr,Ti)O-3 film (PZT) (bulk scenario) and inhibition of the growth of opposite domains due to the nucleus suppression at the electrode interfaces (interface scenario), is proposed. In addition, a new electric treatment able to significantly suppress P-r(s) in Pt-PZT-Pt ferroelectric

A theoretical study on the effect of spontaneous polarization screening on the dielectric response of ferroelectric films with 180 degrees domains going through the film thickness (through-domains) is presented. It has been shown by several researchers tha ...

The results of structural and electrical characterizations of SrTiO3 thin films deposited onto MgO and LaAlO3 substrates by pulsed laser deposition technique are presented. The influence of substrate and annealing procedure on the crystalline structure and dielectric properties of these ferroelectric thin films are investigated. The obtained experimental data are analyzed in terms of the Landau theory taking into account the room-temperature lattice mismatch of the ferroelectric and substrates as well as th

We theoretically study an optomechanical system which consists of a two-sided cavity and a mechanical membrane that is placed outside of it. The membrane is positioned close to one of its mirrors, and the cavity is coupled to the external light field throu ...

The properties of the cation vacancy and the Te antisite, two dominant defects in CdTe and Cd1-xZnxTe alloys grown in Te-rich conditions, are examined using first-principles calculations. First, the structure, electronic levels, and migration paths of V-Cd ...

Direct observation of polarization distribution at nanoscale by scanning force microscopy across partially etched Pb(Zr,Ti)O-3 film ferroelectric capacitors with size 2x3 mum and preferential orientation (111) has revealed an anomalous polarization pattern characterized by polarization inversion in the center of the capacitor. This self-structured pattern is reproducible and independent on the spontaneous polarization orientation, but strongly influenced by the film texture and capacitor size. In particular

The size, shape, and polarization orientation of fatigued areas formed during the suppression of the switchable polarization (P-r(s)) (fatigue) in Ft-FZT-Pt ferroelectric capacitors (FECAPs), were observed by means of atomic force microscopy and by imaging the phase of the piezoelectric vibration induced by a low ac field applied between the top and bottom electrodes. In the virgin state (FECAP as prepared), the pattern of the polarization domains with opposite orientation was randomly distributed with typi

Recent progress in integrating ferroelectrics directly on silicon opens the exciting possibility of implementing ferroelectric-semiconductor devices [1]. One of the major problems for such integration is the instability of the ferroelectric state in very t ...

The surface impedance of type-II superconductors in the mixed state has been measured as a function of the magnetic field in the low-frequency limit. At the low magnetic fields close to the lower critical field the surface impedance was observed to be proportional to the vortex density, whereas at higher fields a crossover to the square-root dependence on the vortex density was observed. This behavior agrees with the two-mode electrodynamics in which the penetration of electromagnetic fields into the superc

The behavior of dielectric loss in SrTiO3 thin films at different microwave frequencies under the dc bias voltage applied is analyzed. Two types of differently processed SrTiO3 thin films (as deposited and oxygen-annealed) deposited by the pulse laser deposition technique onto MgO single crystal substrate are investigated. The half-wave microstrip resonator with the resonance frequencies being 8 and 16 GHz at the first and second resonance modes respectively was used for the microwave characterization of th

Alexander Tagantsev

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Space-charge influenced injection model for conduction in Pb(ZrxTi1-x)O-3 thin films

Non-Kolmogorov-Avrami switching kinetics in ferroelectric thin films

Microscopic aspects of the region-by-region polarization reversal kinetics of polycrystalline ferroelectric Pb(Zr,Ti)O-3 films

Kinetics of polarization reversal in ferroelectric films: role of domain nucleation and domain wall motion

Upper bounds for flexoelectric coefficients in ferroelectrics

Polarization Reversal in BiFeO3 Capacitors: Complex Behavior Revealed by PFM

Dielectric response and structural features of Pb(Sc1/2Ta1/2)O-3 (PST) sol-gel derived thin films

Constant-current study of dielectric breakdown of Pb(Zr,Ti)O-3 ferroelectric film capacitors

Mechanism of polarization response and dielectric non-linearity of PbMg1/3Nb2/3O3 relaxor ferroelectric

Physics and applications of charged domain walls

Discrimination between bulk and interface scenarios for the suppression of the switchable polarization (fatigue) in Pb(Zr,Ti)O-3 thin films capacitors with Pt electrodes

Effect of spontaneous polarization screening on dielectric response of ferroelectric polydomain films

Shift of phase transition temperature in strontium titanate thin films

Dissipative optomechanical coupling with a membrane outside of an optical cavity

Cation-site intrinsic defects in Zn-doped CdTe

Unusual size effect on the polarization patterns in micron-size Pb(Zr,Ti)O-3 film capacitors

Direct observation of region by region suppression of the switchable polarization (fatigue) in Pb(Zr,Ti)O-3 thin film capacitors with Pt electrodes

Control of the Screening Ability at a Ferroelectric-Semiconductor Interface

Magnetic-Field Dependence of the Surface Impedance in the Mixed-State of Type-Ii Superconductors

Intrinsic and extrinsic loss contributions in SrTiO3 thin films at microwave frequencies