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Deutscher, G.
Proceedings of the International Workshop on Anharmonic Properties of High - Tc Cuprates1995
Proceedings of the International Workshop on Anharmonic Properties of High - Tc Cuprates1995
AbstractAbstract
[en] It is well known that retardation effects are essential to allow the attractive part of the electron-electron interaction (for instance, phonon mediated) to overcome the Coulomb repulsion. In new superconductors such as the cuprates for which the interaction is a priori unknown, it is therefore essential to determine the retarded and non retarded parts of the interaction. We show how this can be achieved by an analysis of Sharvin contact measurements between a noble metal tip and a cuprate. It turns out that both the retarded and non retarded parts are large, the former being however larger than the later
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Mihailovic, D.; Ruani, G.; Kaldis, E.; Mueller, K.A. (eds.); 296 p; ISBN 981-02-2180-0;
; 1995; p. 196-203; International Workshop on: Anharmonic Properties of High - Tc Cuprates; Bled (Slovenia); 1-6 Sep 1994; 15 ref.

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Ambrosch-Draxl, C.; Abt, R.; Knoll, P.
Funding organisation: Fonds zur Forderung der wissenschaftlichen Forschung (Austria); Jubilaumsfonds der Osterreichischen Nationalbank (Austria)
Proceedings of the International Workshop on Anharmonic Properties of High - Tc Cuprates1995
Funding organisation: Fonds zur Forderung der wissenschaftlichen Forschung (Austria); Jubilaumsfonds der Osterreichischen Nationalbank (Austria)
Proceedings of the International Workshop on Anharmonic Properties of High - Tc Cuprates1995
AbstractAbstract
[en] We investigate the changes of the total energy, the electronic bands, and the dielectric function with the displacement of the apical oxygen position in YBa2Cu3O7 by LAPW-calculations. From these data we calculate the corresponding vibronic Raman-spectrum. Anharmonic terms of the vibrational potential and higher order derivatives of the dielectric function are taken into account. We find excellent agreement with experimental data for the phonon frequency as well as for the intensities of fundamental and overtone spectra within a wide temperature range
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Mihailovic, D.; Ruani, G.; Kaldis, E.; Mueller, K.A. (eds.); 296 p; ISBN 981-02-2180-0;
; 1995; p. 212-219; International Workshop on: Anharmonic Properties of High - Tc Cuprates; Bled (Slovenia); 1-6 Sep 1994; 17 ref., 7 fig.

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Poberaj, I.; Mertelj, T.; Mihailovic, D.
Funding organisation: European Commission (Belgium)
Proceedings of the International Workshop on Anharmonic Properties of High - Tc Cuprates1995
Funding organisation: European Commission (Belgium)
Proceedings of the International Workshop on Anharmonic Properties of High - Tc Cuprates1995
AbstractAbstract
[en] Using pulsed Raman spectroscopy, we directly examined the intrinsic apical O potential in insulating YBa2Cu3O6.25 and metallic YBa2Cu3O6.9. We selectively excited the apical O vibration mode with ultra short laser pulses to obtain a 'hot' apical O vibration mode in a 'cold' bulk phonon background. Measurements showed that the apical O phonon frequency shift and linewidth change are much smaller in the case of selective heating of the apical O vibration mode compared to bulk heating. The results agree well with theoretical predictions and indicate a strong influence of surrounding lattice ions on the apical O potential. (author)
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Mihailovic, D.; Ruani, G.; Kaldis, E.; Mueller, K.A. (eds.); 296 p; ISBN 981-02-2180-0;
; 1995; p. 244-247; International Workshop on: Anharmonic Properties of High - Tc Cuprates; Bled (Slovenia); 1-6 Sep 1994; 9 ref., 2 figs.

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[en] The response of point contacts between tantalum, copper or niobium and YBa2Cu3O7-δ ceramics to microwave and optical electromagnetic radiation is studied. The ceramics inhomogeneous composition requires the effect of radiation on the circuit resistive elements be taken into account, particularly at high biases
Original Title
Priroda otklika kontaktov so sverkhprovodyashchimi oksidami na ehlektromagnitnoe izluchenie
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[en] Possibility of high-temperature superconductivity in high-correlated systems of 3d- and 2-p-electrons with orbital degeneration is studied on the basis of kinematic mechanism. Phase diagrams of models of HTS oxides with eg2-electrons are calculated
Original Title
Vysokotemperaturnaya sverkhprovodimost' v oksidnykh sistemakh perekhodnykh metallov s vyrozhdennymi 3d-ehlektronami
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CHALCOGENIDES, COPPER COMPOUNDS, DIAGRAMS, ELECTRIC CONDUCTIVITY, ELECTRICAL PROPERTIES, ENERGY LEVELS, FUNCTIONS, INFORMATION, MATHEMATICAL OPERATORS, NICKEL COMPOUNDS, OXIDES, OXYGEN COMPOUNDS, PHYSICAL PROPERTIES, QUANTUM OPERATORS, RARE EARTH COMPOUNDS, SUPERCONDUCTORS, TRANSITION ELEMENT COMPOUNDS
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[en] The flux creep rate at 77.3 K for the fields below 2000 Oe, and the relation between flux creep rate and temperature for the fields of 150, 300 Oe have been experimentally studied in Bi(Pb) SrCaCuO bulk superconductor. The flux pinning potential U0 is estimated. There is a decrease of flux pinning potential U0 with the increase of temperature above 77.3 K in a certain field
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[en] The samples of YBa2-xSrxCu3O7-δ (x = 0.000, 0.299) were prepared. Their superconducting transition temperatures (Tc) were measured. The results show that Tc decreases when Sr atoms substitute for Ba atoms partially in the sample. Their crystal structures have been measured by neutron diffraction method, with their oxygen defect values (δ) being obtained. The reason for the decrease of Tc is discussed primarily from these experimental results
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Numerical Data
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ALKALINE EARTH METAL COMPOUNDS, ALKALINE EARTH METALS, BARIUM COMPOUNDS, CHALCOGENIDES, COHERENT SCATTERING, COPPER COMPOUNDS, DATA, DIFFRACTION, ELECTRIC CONDUCTIVITY, ELECTRICAL PROPERTIES, ELEMENTS, INFORMATION, METALS, NUMERICAL DATA, OXIDES, OXYGEN COMPOUNDS, PHYSICAL PROPERTIES, SCATTERING, STRONTIUM COMPOUNDS, THERMODYNAMIC PROPERTIES, TRANSITION ELEMENT COMPOUNDS, YTTRIUM COMPOUNDS
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[en] The movements of the flux lines in the YBa2Cu3O7-δ epitaxial film have been studied by Hall effect and the broadening of the resistance-temperature curves(R-T curves) in the magnetic field. From the broadened RT curves the exponent relation is obtained between the value of the activation energy of the flux creep and the value of the field. From the measurements of the Hall coefficient RH the unusual variation of the Hall coefficient corresponding to the broadening of the R-T curves is found. All of the variations in the R-T curves as well as the RH-H curves have been also discussed by the vortex glass model, exploring the laws of the flux creep in different ways
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[en] The microstructure of BiSrCaCuO superconductor has been studied. Bi2Sr2Ca2Cu3Oy phase with Tc = 110 K and Bi2Sr2CaCu2Oy phase with Tc = 80 K are existed in the samples. The Tc of superconductor depends on the proportion and the distribution state of the two phases. Pb dopping is benificial to the formation and stabilization of high TC phase. The sintering process influences the microstructure of the superconductivity of the samples
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ALKALINE EARTH METAL COMPOUNDS, BISMUTH COMPOUNDS, CALCIUM COMPOUNDS, CHALCOGENIDES, COHERENT SCATTERING, COPPER COMPOUNDS, CRYSTAL STRUCTURE, DIAGRAMS, DIFFRACTION, ELECTRIC CONDUCTIVITY, ELECTRICAL PROPERTIES, FABRICATION, INFORMATION, OXIDES, OXYGEN COMPOUNDS, PHYSICAL PROPERTIES, SCATTERING, SPECTRA, STRONTIUM COMPOUNDS, THERMODYNAMIC PROPERTIES, TRANSITION ELEMENT COMPOUNDS
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[en] The analysis of a previous paper, in which it was shown that the energy for the Aharonov-Bohm effect could be traced to the interaction energy between the magnetic field of the electron and the background magnetic field, is extended to cover the case in which the magnetic field of the electron is shielded from the background magnetic field by a superconducting material. The paradox that arises from the fact that such a shielding would apparently preclude the possibility of an interaction energy is resolved and, within the limits of the ideal situation considered, the observed experimental result is derived. 7 refs
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