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Field effect
About: Field effect is a research topic. Over the lifetime, 4018 publications have been published within this topic receiving 92613 citations.
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TL;DR: In this article, a nematic material in which e∥ exhibits a dielectric loss in the audio-frequency range is reported, and the activation energy for the loss is 0.91 eV.
Abstract: A new nematic material in which e∥ exhibits a dielectric loss in the audio‐frequency range is reported. At 25 °C Δ e=(e∥−e⊥) reverses sign at 2.5 kHz and can be as positive as 6.2 at low frequencies and as negative as −2.2 at high frequencies; the activation energy for the loss is 0.91 eV. The availability of a dielectric anisotropy of either sign depending on the frequency of the applied field allows the electrical orientation of the material with its optic axis either parallel or perpendicular to the electrodes. The possibilities for improving the voltage threshold and dynamic response of electro‐optical effects by means of a two‐frequency addressing scheme are demonstrated.
114 citations
TL;DR: In this article, the properties of poly(alkylthiophenes) in solution are found to have a profound impact on the self assembly process and thus the microstructural and electrical properties of the resultant thin films.
Abstract: The properties of poly(alkylthiophenes) in solution are found to have a profound impact on the self assembly process and thus the microstructural and electrical properties of the resultant thin films. Ordered supramolecular precursors can be formed in regioregular poly(3-hexylthiophene) (P3HT) solutions through the application of low intensity ultrasound. These precursors survive the casting process, resulting in a dramatic increase in the degree of crystallinity of the thin films obtained by spin coating. The crystallinity of the films is tunable, with a continuous evolution of mesoscale structures observed as a function of ultrasonic irradiation time. The photophysical properties of P3HT in solution as well in the solid state suggest that the application of ultrasound leads to a π stacking induced molecular aggregation resulting in field effect mobilities as high as 0.03 cm2 V−1 s−1. A multiphase morphology, comprising short quasi-ordered and larger, ordered nanofibrils embedded in a disordered amorphous phase is formed as a result of irradiation for at least 1 min. Two distinct regions of charge transport are identified, characterized by an initial sharp increase in the field effect mobility by two orders of magnitude due to an increase in crystallinity up to the percolation limit, followed by a gradual saturation where the mobility becomes independent of the thin film microstructure.
114 citations
TL;DR: In this article, the influence of the applied dc current on the resistance of epitaxial thin films in the absence of a magnetic field was studied and a significant change in the ratio of the peak resistance at different currents or current resistance was found.
Abstract: Electric-current-dependent resistance has been studied in epitaxial thin films of La0.7Ca0.3MnO3 and La0.85Ba0.15MnO3. Attention was focused at the influence of the applied dc current on the resistance of these epitaxial thin films in the absence of a magnetic field. A significant change in the ratio of the peak resistance at different currents or current resistance was found to be ∼23%–26% with a current density up to 8×104 Acm−2. For both La0.7Ca0.3MnO3 and La0.85Ba0.15MnO3 compounds, the dependence of the measured resistance on the current revealed a good linear relationship. Although the nature behind such an effect has not been well understood yet, the feature that the resistance in doped manganese oxides could be easily controlled by the electric current should be of interest for various applications such as field effect devices.
113 citations
TL;DR: In this paper, the authors present an approach for controlling the rate of electroosmosis due to a first electric potential in an electrically insulating capillary, in which a second electric potential is applied between the electrically-insulating walls of the capillary and a liquid within the liquid.
113 citations
Book•
01 Jan 2000
TL;DR: In this article, the authors present a Chronological Development of Crystal Field Models and the Effective Crystal Field Potential, including the effect of charge transfer, charge penetration, and charge exchange, with a focus on the nonorthogonality of wave functions.
Abstract: Chapter headings: Introduction. Parameterization of Crystal Field Hamiltonian. The Effective Crystal Field Potential. Chronological Development of Crystal Field Models. Ionic Complex or Quasi-Molecular Cluster. Generalized Product Function. Point Charge Model (PCM). One-Configurational Model with Neglecting the Non-Orthogonality. The Charge Penetration and Exchange Effects.The Exclusion Model. One-configurational Approach with Regards to Non-Orthogonality of the Wave Functions. Covalency Contribution, i.e. The Charge Transfer Effect. Shielding and Antishielding Effect: Contributions from Closed Electron Shells. Electrostatic Crystal Field Contributions with Consistent Multipolar Effects. Polarization. Crystal Field effect in the Stevens Perturbation Approach. Specific Mechanisms of Metallic States Contributing to the Crystal Field Potential. Virtual Bound State Contribution to the Crystal Field Potential. Hybridization or Covalent Mixing Between Localized States and Conduction Band States in Metallic Crystals. Density Functional Theory Approach. Analysis of the Experimental Data. Interpretation of Crystal Field Parameters with Additive Models. Lattice Dynamics Contribution. Extension of the Crystal Field Potential Beyond the One-Electron Model. Appendices. Author index. Keyword index.
112 citations