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Author Duran, C.; Yazyi, J.; de la Cruz, F.; Bishop, D.J.; Mitzi, D.B.; Kapitulnik, A.
Title Flux-lattice melting, anisotropy, and the role of interlayer coupling in Bi-Sr-Ca-Cu-O single crystals Type Journal Article
Year 1991 Publication Physical Review B Abbreviated Journal PRB
Volume 44 Issue 14 Pages (down) 7737-7740
Keywords
Abstract We have used the high-Q mechanical-oscillator technique to probe the vortex-lattice structure in high-quality Bi-Sr-Ca-Cu-O single crystals over a wide range of magnetic fields (200 Oe to 40 kOe), and relative orientations θ between the magnetic field and the crystalline c^ axis. In addition to the large softening and dissipation peak previously observed and interpreted as due to flux-lattice melting, another distinctly different peak at higher temperatures is seen. The temperatures where the dissipation peaks take place are solely defined by the parallel component of the field cosθ, while the restoring force on the oscillator is due to both field components. We suggest that the two peaks are due to the softening of interplanar coupling at the low-temperature peak, and melting or depinning of the two-dimensional pancake vortices at the higher-temperature peak.
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Publisher American Physical Society Place of Publication Editor
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Notes Rapid Communication Approved no
Call Number BT @ pedrazp @ 10.1103/PhysRevB.44.7737 Serial 543
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Author Núñez Regueiro, M.; Esquinazi, P.; Izbizky, M.A.; Duran, C.; Castello, D.; Luzuriaga, J.; Nieva, G.
Title Evidence of tunneling systems through thermal and acoustic measurements in ceramic materials Type Journal Article
Year 1988 Publication Physica C: Superconductivity and its applications Abbreviated Journal Physica C
Volume 153-155 Issue PART 2 Pages (down) 1016-1017
Keywords Acoustic Variables Measurement--Wave Velocity; Ceramic Materials--Thermal Conductivity; Europium Barium Copper Oxides; Superconducting Materials
Abstract We have neasured the sound velocity, internal friction, thermal conductivity and specific heat of La-based and (Y/Eu)- based ceramics. The low temperature data can be understood in terms of the Tunneling Model assuming the existence of Tunneling Systems (TS). From these measured properties we obtain values for the parameter C=P?2/?v2, where P is the density of states of TS, ? the coupling constant between phonons and TS, ? the mass density and v the sound velocity close to those obtained for amorphous and “orientational” disordered crystalline materials. Our data would indicate that the TS are intrinsic defects independent of the sample porosity.
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ISSN 09214534 (ISSN) ISBN Medium
Area Expedition Conference International Conference on High Temperature Superconductors and Materials and Mechanisms of Superconductivity
Notes Export Date: 28 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: Regueiro, M.N.; Centro At Approved no
Call Number BT @ luzuriag @ Serial 496
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Author Rodríguez, E.; Duran, C.; Luzuriaga, J.; de la Cruz, F.; Fainstein, C.
Title Anomalous behaviour of the vortex structure in Bi4Ca2Sr4Cu4O16+y measured with a vibrating reed at low magnetic fields Type Journal Article
Year 1990 Publication Physica C: Superconductivity Abbreviated Journal Physica C
Volume 165 Issue 3-4 Pages (down) 315-320
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Abstract The response of the vortex structure in ceramic samples of Bi4Ca2Sr4Cu4O16+y has been measured by means of a vibrating reed technique in magnetic fields below 0.2 T. An anomally in the response of the reed is seen at temperatures of around 30 to 40 K, well below the critical temperature, indicating a transition similar to that attributed to a melting of the Flux Line Lattice. There is a shift in the temperature at which the anomaly is detected when one increases the driving force on the reed, while the dissipation shows a maximum associated to the transition which scales with the square of the applied magnetic field. Comparison with magnetization measurements shows that there is non-zero critical current at the same temperature where the anomalous behaviour is detected with our technique.
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ISSN 0921-4534 ISBN Medium
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Notes ISI:A1990CN49800014 Approved no
Call Number BT @ hernan @ Serial 261
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