| Records |
| Author |
Núñez Regueiro, M.; Izbizky, M.A.; Esquinazi, P. |
| Title |
Thermal conductivity and “disorder” in high temperature superconductors |
Type |
Journal Article |
| Year |
1988 |
Publication |
Solid State Communications |
Abbreviated Journal |
Solid State Commun. |
| Volume |
67 |
Issue |
4 |
Pages |
401-404 |
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| Abstract |
We analyze the controversial thermal conductivity results on high temperature superconductors by scaling the data with material parameters to compare them to other materials with similar behaviour. We show that they have the same general features observed in amorphous and disordered crystalline materials. Possible origins of the disorder are discussed. |
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| ISSN |
0038-1098 |
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BT @ pedrazp @ |
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583 |
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| Author |
Rodriguez, E.; Luzuriaga, J.; Núñez Regueiro, M.; Fainstein, C. |
| Title |
Low temperature internal friction peak in high Tc superconductors |
Type |
Journal Article |
| Year |
1991 |
Publication |
Solid State Communications |
Abbreviated Journal |
Solid State Commun. |
| Volume |
77 |
Issue |
10 |
Pages |
777-780 |
| Keywords |
Ceramic Materials; Oxides – Acoustic Properties; Yttrium Compounds – Acoustic Properties; Acoustic Variables Measurement; Attenuation Peak; Calcium Compounds; Low Temperature Internal Friction Peak; Strontium Compounds; Thermally Activated Relaxation Behavior; High Temperature Superconductors |
| Abstract |
We measure the internal friction Q-1 in YBa2Cu3O7-x and Bi2Sr2CaCu2O8+x samples. At temperatures near 35 K for KHz frequencies we observe an attenuation peak. In the case of YBa2Cu3O7-x, assuming a thermally activated relaxation behaviour, we are able to show that it corresponds to the same process as other peaks observed at higher frequencies. For Bi2Sr2CaCu2O8+x this is not the case, and the origin of the peak, found in all the measured samples, remains unknown. |
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0038-1098 |
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ISI:A1991FA71400006 |
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no |
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BT @ hernan @ |
Serial |
256 |
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| Author |
Castello, D.; Jaime, M.; Núñez Regueiro, M. |
| Title |
Thermal conductivity of high temperature superconductor TlBaCaCuO |
Type |
Journal Article |
| Year |
1991 |
Publication |
Solid State Communications |
Abbreviated Journal |
Solid State Commun. |
| Volume |
79 |
Issue |
11 |
Pages |
967-970 |
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| Abstract |
We have measured the thermal conductivity of ceramic samples of TlBaCaCuO between 2 and 250 K. At high temperatures it follows a constant behaviour down to the superconducting transition temperature where a sudden increase of the thermal conductivity occurs, attributed to reduced phonon scattering by condensating electrons. At low temperatures a T2 law is observed, confirming the assumption that it is a common feature in most of the high temperature superconducting oxides. Phonon scattering against tunneling systems analogous to those found in amorphous solids can explain this behaviour. |
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0038-1098 |
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no |
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BT @ pedrazp @ |
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581 |
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| Author |
Núñez Regueiro, M.; Esquinazi, P.; Izbizky, M.A.; Durán, C.; Castello, D.; Luzuriaga, J. |
| Title |
Tunneling systems in high temperature superconductors |
Type |
Journal Article |
| Year |
1988 |
Publication |
Annales de Physique |
Abbreviated Journal |
Ann. Phys. Fr. |
| Volume |
13 |
Issue |
5 |
Pages |
401-406 |
| Keywords |
acoustic wave absorption; acoustic wave velocity; barium compounds; high temperature superconductors; lanthanum compounds; rare earth compounds; strontium compounds; superconductive tunnelling; thermal conductivity of solids; tunnelling systems; high temperature superconductors; thermal conductivity; sound attenuation; sound velocity; model; low temperature specific heat; La Sr Cu O |
| Abstract |
We have measured the thermal conductivity, sound attenuation and relative variation of sound velocity of compounds of the La-Sr-Cu-O and RBa2Cu3O7 families, where R is a rare-earth. We have found that all these properties can be quantitatively correlated within a tunneling system model similar to that used in amorphous materials. This interpretation would naturally explain the anomalous linear term of the low temperature specific heat observed in these materials. |
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0003-4169 |
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ISI:A1988Q715000009 |
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no |
| Call Number |
BT @ hernan @ |
Serial |
264 |
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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 |
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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09214534 (ISSN) |
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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 |
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no |
| Call Number |
BT @ luzuriag @ |
Serial |
496 |
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| Author |
Núñez Regueiro, M; Castello, D.; Jaime, M. |
| Title |
Thermal conductivity of high temperature superconductors |
Type |
Journal Article |
| Year |
1991 |
Publication |
Physica B: Condensed Matter |
Abbreviated Journal |
Physica B |
| Volume |
169 |
Issue |
1-4 |
Pages |
631-632 |
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| Abstract |
We have measured the thermal conductivity of Tl1Ba2Cu3O9 and of the related compounds CuO and La2CuO4. For the superconducting sample we observe the characteristic T2 behaviour at low temperatures, that does not appear in the non-superconducting samples. The superconducting transition and the antiferromagnetic ordering are detected by our measurements. |
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0921-4526 |
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no |
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BT @ pedrazp @ |
Serial |
582 |
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| Author |
Durán, C.; Esquinazi, P.; Fainstein, C.; Núñez Regueiro, M. |
| Title |
Anomalies in the internal friction and sound velocity in YBa2Cu3O7-x and EuBa2Cu3O7-x superconductors |
Type |
Journal Article |
| Year |
1988 |
Publication |
Solid State Communications |
Abbreviated Journal |
Solid State Commun. |
| Volume |
65 |
Issue |
9 |
Pages |
957-961 |
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Internal friction Q-1 and Young Modulus sound velocity vE measurements at 1 kHz in YBa2Cu3O7?x and EuBa2Cu3O7?x polycrystalline samples reveal anomalies at the superconducting transition and at not, vert, similar37 K. The anomaly in vE at not, vert, similar90 K is accompanied by an absorption peak and is in agreement with published ultrasonic measurements, suggesting a lattice deformation at the superconducting transition. |
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0038-1098 |
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no |
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BT @ pedrazp @ |
Serial |
569 |
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| Author |
Izbizky, M.A.; Núñez Regueiro, M.; Esquinazi, P.; Durán, C.; Fainstein, C. |
| Title |
Phonon transport in superconducting EuBa2Cu3O7-x |
Type |
Journal Article |
| Year |
1988 |
Publication |
Physics Letters A |
Abbreviated Journal |
Phys. Lett. A |
| Volume |
129 |
Issue |
1 |
Pages |
71-75 |
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We have measured the thermal conductivity, Young modulus sound velocity and internal friction of a polycrystalline sample of the ceramic superconductor EuBa2Cu3O7-x. The low temperature data can be quantitavely understood assuming the interaction of phonons with tunneling systems. |
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0375-9601 |
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no |
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BT @ pedrazp @ |
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571 |
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Núñez Regueiro, M.; Castello, D.; Izbizky, M.A.; Esparza, D.; D'Ovidio, C. |
| Title |
Anomalous thermal conductivity of La2-xSrxCuO4: Possibility of a polaronic glass |
Type |
Journal Article |
| Year |
1987 |
Publication |
Physical Review B |
Abbreviated Journal |
Phys. Rev. B |
| Volume |
36 |
Issue |
16 |
Pages |
8813-8815 |
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| Abstract |
e present measurements of the thermal conductivity of La2CuO4 and La1.85Sr0.15CuO4. The results on the pure sample show that lattice conduction is predominant with a T1.8 dependence at low temperatures and a strong T-independent scattering above 30 K. We observe a similar behavior for the superconductor but with a T1.4 law at low temperature and a small electronic contribution in the normal state. These results together with the behavior of the specific heat and sound attenuation are consistent with the existence of a two-level tunneling system for an amorphous state. |
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American Physical Society |
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BT @ pedrazp @ 10.1103/PhysRevB.36.8813 |
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574 |
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Izbizky, M.A.; Núñez Regueiro, M.; Esquinazi, P.; Fainstein, C. |
| Title |
Thermal conductivity and superconductivity in EuBa2Cu3O7-x |
Type |
Journal Article |
| Year |
1988 |
Publication |
Physical Review B |
Abbreviated Journal |
Phys. Rev. B |
| Volume |
38 |
Issue |
13 |
Pages |
9220-9223 |
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American Physical Society |
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BT @ pedrazp @ 10.1103/PhysRevB.38.9220 |
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573 |
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