Literatura académica sobre el tema "Isolants Mott – Propriétés électriques"
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Tesis sobre el tema "Isolants Mott – Propriétés électriques"
Koussir, Houda. "Multiscale study of the electric field induced transition in the Mott phase of GaMo4S8 crystals and TaSe2 monolayers". Electronic Thesis or Diss., Université de Lille (2022-....), 2024. http://www.theses.fr/2024ULILN004.
Texto completoIn the realm of condensed matter physics, Mott insulators are essential for exploring complex electronic phenomena, with significant implications for high-temperature superconductivity and quantum spin liquids. This thesis investigates two types of such materials, distinguished by their dimensionality : GaMo4S8 crystals and monolayer 1T-TaSe2.After presenting their properties in the first chapter, the second chapter addresses the local-scale characterization techniques used to characterize both materials, namely scanning tunneling microscopy and spectroscopy for structural and electronic studies, and multi-tip scanning tunneling microscopy for transport measurements. The latter technique was particularly employed to analyze transport in GaMo4S8. The study then delved into the material response to external electric fields, examining the threshold electric field in relation to the electrode geometry and exploring the temporal evolution of switching times in connection with inter-electrode distances. The achievement of volatile transitions opens prospects for applications such as the operation of a microneuron at room temperature.To enhance the control over phase transition properties of Mott insulators, it is beneficial to consider two-dimensional systems where the current flow is restricted within the crystal plane. The final chapter focuses on the 1T phase of TaSe2, epitaxially grown on gallium phosphide (GaP) semiconductor substrates. Low-temperature scanning tunneling microscopy studies reveal that 1T-TaSe2 monolayers exhibit not only the characteristic charge density modulation (Star of David) of the charge density wave phase but also a unique Moiré pattern due to the monolayer interaction with the GaP substrate. Scanning tunneling spectroscopy has identified a bandgap, hallmark of the Mott insulating state. This state is further substantiated by temperature-dependent transport measurements that show the persistence of the insulating phase up to 400 kelvins. Notably, spectroscopic measurements with varying tip-to-surface distances have unveiled insulator to metal transitions at low temperatures. The observation of such transitions suggests that this large-scale heterostructure could be a material of choice for neuromorphic applications
Amsalem, Patrick. "Etude spectroscopique de films de phtalocyanines adsorbés sur surfaces métalliques". Aix-Marseille 1, 2008. http://www.theses.fr/2008AIX11082.
Texto completoThe initial steps of the interface formation between metallo-phthalocyanines (ZnPc et ZnPcCl8) and Ag(111) or Ag(110) surfaces have been studied by Scanning tunnelling microscopy, Low-energy electron diffraction, Photoelectron spectroscopy and High-resolution electron energy loss spectroscopy. On both surfaces, the molecular self-assembly leads to the formation of long range ordered monolayers at room temperature. For each system, upon adsorption, the molecules are significantly distorted and charge transfers from the surface to molecules are detected. The resulting doped monolayers are found metallic or insulating, depending on the structural details of the molecular networks. This link between structural and electronic properties is rationalized in terms of electronic correlations. Consequently, the monolayers that retain insulating properties upon electronic doping can be described in terms of Mott-Hubbard insulator. Such results provide new insights for the understanding of the fundamental phenomena at organic/metal interfaces and are susceptible to be extended to other organics adsorbed on solid surfaces
Guiot, Vincent. "Comportement hors équilibre des isolants de Mott sous champ électrique : transition résistive par effet d'avalanche électronique dans les composés AM4X8 (A=GA, Ge ; M=V,Nb,Ta;X=S,Se) et Ni (S, Se)2". Nantes, 2011. http://www.theses.fr/2011NANT2119.
Texto completoDuring the last quarter of century, major breakthroughs in Solid State Physics (superconductivity, magnetoresistance) occurred in the vicinity of the Mott metal-insulator transition (MIT). This transition is due to electronic correlations and is usually controlled by electronic doping and by pressure. Despite its high applicative potential, control of the MIT by electric field still remains less studied. Recently, a peculiar electric pulse induced resistive switching (EPIRS) was discovered in the family of correlated compounds AM 4 X 8 (A= Ga, Ge; M= V, Nb, Ta; X= S, Se). In this PhD thesis, the Mott insulating electronic state of these compounds is firstly investigated. We show then that electric fields above threshold values E,h as low as I kV/cm allow to break the Mott insulating state of these materials. This phenomenon appears to be of purely electronic origin and can be pinned to cause a non volatile transition. A study of the new solid solution GaTa4(Se,Te)s, developed on purpose, demonstrates the E,h dependence with the Mott gap. Comparison with conventional semiconductors behaviour under electric field strongly suggests that this transition corresponds to an electronic avalanche, in contrast with theoretical predictions of a Zener effect. Peculiar dynamics of transition and strong electro-mechanical coupling experimentally observed are suggested to originate from the Mott insulating state of the compounds. A similar study of the Ni(S,Se)2 solid solution and of the organic compound K-(BEDT-TTF)2Cu[N(CN) 2 ]Cl confirms the generalization of this electronic avalanche effect to other Mott insulators
Haas, Vincent. "Caractérisation 3D des charges électriques dans les isolants polymères minces par imagerie thermoacoustique". Toulouse 3, 1997. http://www.theses.fr/1997TOU30169.
Texto completoTran, Duy Chau. "Propriétés diélectriques de liquides isolants d'origine végétale pour applications en haute tension". Grenoble 1, 2009. http://www.theses.fr/2009GRE10017.
Texto completoFor the environmental, economic or technical reasons, oils based on natural esters were used to replace mineral oil in electrical equipments in low and medium voltage. This work consists on characterization of a mixture (RS50) of low viscosity natural esters based on rapeseed oil for applications in high voltage transformers. The influence of humidity, temperature, particle content and thermal aging on its dielectric properties such as permittivity, conductivity, losses and electrical strength was highlighted. The RS50 has a high-water solubility, its conductivity, permittivity and losses are both higher than those of mineral oil but these differences are reduced in aged oils. Its electrical strength is similar to mineral oil even after aging. However, an analysis more precise of prebreak down and breakdown phenomena in specific configurations have shown that natural esters are less favorable for high voltage applications than mineral oil. In parallel, a methodological study was carried out. Advantage of using the frequency spectroscopy measuring method for the characterization of insulating liquids is highlighted. The validity of conditions for the dielectric strength measurement in the liquid insulation, which is traditionally imposed following the standards, was also discussed
Hadid, Mohammed Abderahmane. "Conception d'un dispositif de mesure des charges injectées dans les polymères sous champ alternatif divergent : application au vieillissement électrique". Toulouse 3, 1992. http://www.theses.fr/1992TOU30249.
Texto completoChailan, Jean-François. "Contribution des spectrométries mécanique et diélectrique à l'étude du vieillissement d'élastomères en ambiance nucléaire". Lyon 1, 1993. http://www.theses.fr/1993LYO10236.
Texto completoGuerret-Piecourt, Christelle. "Effets de la génération, de l'injection et du piégeage des charges électriques sur les propriétés des isolants". Habilitation à diriger des recherches, Ecole Centrale de Lyon, 2005. http://tel.archives-ouvertes.fr/tel-00128125.
Texto completoDubost, Vincent. "Étude par microscopie/spectroscopie tunnel de la transition isolant/métal induite par pulses électriques dans GaTa4Se8". Paris 6, 2009. http://www.theses.fr/2009PA066633.
Texto completoIn this PhD thesis, we have studied using scannng tunneling microscopy/spectroscopy the two main phenomena due to interactions between electrons : superconductivity and Mott Metal-Insulator transition. The study of the intercalated graphite CaC6 show that this superconductor is well described by conventionnal BCS theory with a zero temperature gap of 1. 6 +/-0. 2 meV, even if a small spectroscopic broadening suggest a weak anisotropy in the ab plane. The imaging of vortex lattice give for the coherence length extrapolated at zero temperature 38 nanometers. The main part of the manuscript is dedicated to the study of the Electric Pusle Insulator-Metal Transition in the weak Mott Insulator GaTa4Se8. The application of the electric pulse induces the formation of metallic zones in a insulating matrix in the bulk material. These observations provides a natural explanation for the phenomenological model used in transport measurements. The application of voltage sweeps during spectroscopic measurements trigger a local Insulator-Metal transition and for increased biases (V>1. 0V), one can observe a inflation of the surface as an effect of the electric field. The study of electron doped compound Ga0,91Zn0,15Ta4Se8 show that if doping induce a metallicity, the transition induced by the electric pulse is closer to a bandwith controled transition rather than a doping controled transition. This manuscript set the question if this phenomena isintrinsic to GaTa4Se8, or general to the other weak Mott insulators
El, Ourzaz Lahcen. "Mesures diélectriques et caractérisation de matériaux moléculaires". Lyon 1, 1989. http://www.theses.fr/1989LYO10064.
Texto completoLibros sobre el tema "Isolants Mott – Propriétés électriques"
1928-, Elliott R. J. y Ipatova I. P. 1929-, eds. Optical properties of mixed crystals. Amsterdam: North-Holland, 1988.
Buscar texto completoCapítulos de libros sobre el tema "Isolants Mott – Propriétés électriques"
"12 Transport de charges électriques. Conducteurs et isolants. Propriétés électroniques des oxydes". En La chimie des solides, 443–80. EDP Sciences, 2004. http://dx.doi.org/10.1051/978-2-7598-0173-2.c014.
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