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Author Braun, E.; Bürger, A.; Roden, B.; Sereni, J.G.
Title Spin glass-like behaviour of the singlet ground state system: ThTb Type Journal Article
Year (up) 1988 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume 66 Issue 11 Pages 1141-1144
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Abstract We have studied the temperature and field dependence of the magnetic susceptibility, X, on the single-ground-state Th1?nTbn system, in the 0.2 < n < 0.6 concentration range. The characteristic maximum of a spin glass transition was found at a temperature Tg, which increases linearly with the impurity concentration. As expected, the maximum of X is reduced by the increment of the applied magnetic field. The spin glass order parameter, as well as its critical exponent were evaluated by using the Sherrington-Kirkpatrick theory.
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Call Number BT @ pedrazp @ Serial 577
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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 (up) 1988 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume 65 Issue 9 Pages 957-961
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Abstract 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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Call Number BT @ pedrazp @ Serial 569
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Author Civale, L.; Pastoriza, H.; Cruz, F. de la; Guimpel, J.; Nieva, G.; Heintz, J.M.; Durmeyer, O.; Kappler, J.P.
Title Meissner fraction of insulating samples of oxide superconductors Type Journal Article
Year (up) 1989 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume 72 Issue 4 Pages 341-344
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Abstract The tendency towards superconducting granularity with sample degradation is a common feature of oxide superconductors. We present magnetic, transport and calorimetric results in LiTi$4$ which show that the topological tendency to segregate the superconducting state into islands surrounded by thin insulating layers is related to the structure of the material rather than to a mechanism associated to high T$_C$. We emphasize that insulating samples with small Meissner fraction can have a superconducting volume fraction close to unity.
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Call Number BT @ hernan @ civale89 Serial 8
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Author Decca, R.; Osquiguil, E.; de la Cruz, F.; D'Ovidio, C.; Malachevski, M.T.; Esparza, D.
Title Non linear temperature dependence of the resistivity of LaSrCuO: Effects of Sr content Type Journal Article
Year (up) 1989 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume 69 Issue 4 Pages 355-357
Keywords Ceramic Materials; Lanthanum Compounds--Electric Conductivity; Superconductivity; Ceramic Superconductors; Superconducting Materials
Abstract The linear temperature dependence of the electrical resistivity has been taken to be one of the characteristic features of the ceramic superconductors. Measurements of the electrical resistance of the LaSrCuO system in a wide temperature range show that the previous statement is only an approximation valid for some values of the Sr concentration.
Address Applied Research Department, Centro At'omico Bariloche
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Notes Cited By (since 1996): 2; Export Date: 17 April 2009; Source: Scopus; CODEN: SSCOA; Language of Original Document: English; Correspondence Address: Decca, R.; Basic Research Department; Centro At Approved no
Call Number BT @ osquigui @ Serial 414
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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 (up) 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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Notes ISI:A1991FA71400006 Approved no
Call Number 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 (up) 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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Call Number BT @ pedrazp @ Serial 581
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Author Trovarelli, O.; Stickar, P.; Sereni, J.G.; Schmerber, G.; Kappler, J.P.
Title Coexistence of magnetic and non magnetic states in Ce14X51 (X = Au, Ag and Cu) Type Journal Article
Year (up) 1994 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume 89 Issue 5 Pages 421-424
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Abstract Magnetic (chi), thermal(C-p), and transport (p) measurements on Ce(l4)X(51) (X = Au, Ag and Cu) are presented. All these compounds show antiferromagnetic type order at low temperatures, with T-N = 0.9 K (Au), 1.1 K (Ag) and 3.2 K (Cu). Within the Gd14Ag51-type structure the Ce atoms sit in different sublattices denoted by I (2 atoms), II (6 atoms) and III (6 atoms), therefore the results can be interpreted in terms of three different behaviors of Ce depending on its local environment. From the entropy involved in the magnetically ordered (MO) phase it can be established that the Ce-II and Ce-III atoms order in Cel4Au51 and Ce14Ag51, while the Ce-I order in Cel4Cu51. There is a large linear contribution to Cp at T > T-N,T-gamma HT = 0.81 (Au), 1.24 (Ag) and 3.1 (Cu) J/mol K-2, which indicates the coexistence of MO and heavy fermions. In the case of Cel4Cu51, the magnetic contribution to Cp from sublattice Ce-I around T-N,T- resembles that of a modulated system and the characteristic temperatures for Ce-II and Ce-III atoms are estimated from p(T) as:T-K=16 K and >120 K respectively.
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Notes ISI:A1994MX74400003 Approved no
Call Number BT @ hernan @ Serial 107
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Author Grigera, S.A.; Morré, E.; Osquiguil, E.; Nieva, G.; De la Cruz, F.
Title Nonlocal transport properties and size effects in heavily twinned YBa2Cu3O7-delta single crystals Type Journal Article
Year (up) 1998 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume 107 Issue 7 Pages 335-339
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Abstract We demonstrate experimentally that when the vortex correlation length in the liquid state becomes of the order of the sample thickness, size effects dominate the transport properties of the macroscopic vortex structures, implying a nonlocal response in the transformer experiments.
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Notes ISI:000074907100004 Approved no
Call Number BT @ hernan @ Serial 237
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Author Herbsommer, J.A.; Correa, V.F.; Nieva, G.; Pastoriza, H.; Luzuriaga, J.
Title Vortex dynamics in Bi2Sr2CaCu2O8+δ single crystals with planar defects Type Journal Article
Year (up) 2001 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume 120 Issue 2-3 Pages 59-63
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Abstract We have studied the effects of c-axis correlated planar defects on the vortex lattice of Bi$2$Sr$2$CaCu$8$ single crystals using Bitter decoration, transverse ac permeability and X-ray measurements. Our results show that the low field low temperature phase coherent vortex lattice exhibits anisotropic pinning in the presence of these planar defects. Frequency dependent ac permeability measurements show that the ordered solid-liquid transition is first order as in samples free of correlated defects. However, the melting point is detected only when the excitation field is along the defects.
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Call Number BT @ hernan @ herbsommer01 Serial 23
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Author Fasano, Y.; de Seta, M.; Menghini, M.; Pastoriza, H.; de la Cruz, F.
Title Imaging the structure of the interface between symmetries interconnected by a discontinuous transition Type Journal Article
Year (up) 2003 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume 128 Issue 3-4 Pages 51-55
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Abstract We have been able to observe with single particle resolution the interface between two structural symmetries that cannot be interconnected by a continuous transition. By means of an engineered 2D potential that pins the extremity of vortex strings a square symmetry was imposed at the surface of a 3D vortex solid. Using the Bitter decoration technique and on account of the continuous vortex symmetry, we visualize how the induced structure transforms along the vortex direction before changing into the expected hexagonal structure at a finite distance from the surface.
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Call Number BT @ hernan @ fasano03a Serial 18
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