A model for retention on short, intermediate and long time-scale in ferroelectric thin films

We developed a model with no adjustable parameter for retention loss at short and long time scale in ferroelectric thin-film capacitors. We found that the predictions of this model are in good agreement with the experimental observations in the literature. In particular, it explains why a power-law function shows better fitting than a linear-log relation on a short time scale (10^-7 s to 1 s) and why a stretched exponential relation gives more precise description than a linear-log plot on a long time scale (>100 s), as reported by many researchers in the past. More severe retention losses at higher temperatures and in thinner films have also been correctly predicted by the present theory.Comment: 15 pages and 3 figure

Unipolar and bipolar fatigue in antiferroelectric lead zirconate thin films and evidences for switching-induced charge injection inducing fatigue

For the first time, we show that unipolar fatigue does occur in antiferroelectric capacitors, confirming the predictions of a previous work [Appl. Phys. Lett., 94, 072901 (2009)]. We also show that unipolar fatigue in antiferroelectrics is less severe than bipolar fatigue if the driving field is of the same magnitude. This phenomenon has been attributed to the switching-induced charge injection, the main cause for polarization fatigue in ferroelectric and antiferroelectric materials. Other evidences for polarization fatigue caused by the switching-induced charge injection from the nearby electrode rather than the charge injection during stable/quasi-stable leakage current stage are also discussed.Comment: 10 pages and 2 figure

Statistical switching kinetics in ferroelectrics

By assuming a more realistic nucleation and polarization reversal scenario we build a new statistical switching model for ferroelectrics, which is different from either the Kolmogorov-Avrami-Ishibashi (KAI) model or the Nucleation-Limited-Switching (NLS) model. After incorporating a time-dependent depolarization field this model gives a good description about the retardation behavior in polycrystalline thin films at medium or low fields, which can not be described by the traditional KAI model. This model predicts correctly n=1 for polycrystalline thin films at high Eappl or ceramic bulks in the ideal case

On Robust Stability of Limit Cycles for Hybrid Systems with Multiple Jumps

In this paper, we address stability and robustness properties of hybrid limit cycles for a class of hybrid systems with multiple jumps in one period. The main results entail equivalent characterizations of stability of hybrid limit cycles for hybrid systems. The hybrid limit cycles may have multiple jumps in one period and the jumps are allowed to occur on sets. Conditions guaranteeing robustness of hybrid limit cycles are also presented

An Internal Control Evaluation Tool For Advertising Revenue In The Newspaper And Magazine Publishing Industry

Even before the recent economic downturn, the newspaper and magazine publishing industry had been experiencing unprecedented change, with some companies facing an immediate need to either invent a new business model or else cease operations.  The current economic slowdown has, in many cases, exacerbated those challenges.  These trends have had the effect of increasing the risk of fraudulent financial reporting.  The revenue cycle continues to be one of the most important areas for auditors to examine for possible fraud and one for which strong, comprehensive internal controls are especially important (AICPA 2002).  This paper presents an internal control review checklist for advertising revenue in the newspaper and magazine publishing industry.  This checklist may be used by independent auditors as a general benchmark in performing a preliminary evaluation of a company’s internal controls over advertising revenue.  In instances where important internal controls on the checklist have been omitted from the client’s system, the auditor should consider whether the omission increases audit risk.  The checklist may also be used by CFOs or controllers in the industry to help determine whether their company’s internal control system is adequate

Periodic and Localized Solutions of the Long Wave-Short Wave Resonance Interaction Equation

In this paper, we investigate the (2+1) dimensional long wave-short wave resonance interaction (LSRI) equation and show that it possess the Painlev\'e property. We then solve the LSRI equation using Painlev\'e truncation approach through which we are able to construct solution in terms of three arbitrary functions. Utilizing the arbitrary functions present in the solution, we have generated a wide class of elliptic function periodic wave solutions and exponentially localized solutions such as dromions, multidromions, instantons, multi-instantons and bounded solitary wave solutions.Comment: 13 pages, 6 figure

Distribution of Spectral Lags in Gamma Ray Bursts

Using the data acquired in the Time To Spill (TTS) mode for long gamma-ray bursts (GRBs) collected by the Burst and Transient Source Experiment on board the Compton Gamma Ray Observatory (BATSE/CGRO), we have carefully measured spectral lags in time between the low (25-55 keV) and high (110-320 keV) energy bands of individual pulses contained in 64 multi-peak GRBs. We find that the temporal lead by higher-energy gamma-ray photons (i.e., positive lags) is the norm in this selected sample set of long GRBs. While relatively few in number, some pulses of several long GRBs do show negative lags. This distribution of spectral lags in long GRBs is in contrast to that in short GRBs. This apparent difference poses challenges and constraints on the physical mechanism(s) of producing long and short GRBs. The relation between the pulse peak count rates and the spectral lags is also examined. Observationally, there seems to be no clear evidence for systematic spectral lag-luminosity connection for pulses within a given long GRB.Comment: 20 pages, 4 figure

Phase Separation of Bismuth Ferrite into Magnetite under Voltage Stressing

Micro-Raman studies show that under ~700 kV/cm of d.c. voltage stressing for a few seconds, thin-film bismuth ferrite BiFeO3 phase separates into magnetite Fe3O4. No evidence is found spectroscopically of hemite alpha-Fe2O3, maghemite gamma-Fe2O3, or of Bi2O3. This relates to the controversy regarding the magnitude of magnetization in BiFeO3.Comment: 9 pages and 2 figure