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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 1989 Publication (up) 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 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 2003 Publication (up) 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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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 2001 Publication (up) 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 Shalóm, D. E.; Pastoriza, H.
Title Experimental evidence for anisotropic response of a driven vortex lattice Type Journal Article
Year 2003 Publication (up) Solid State Communications Abbreviated Journal Solid State Commun.
Volume 126 Issue 7 Pages 379-383
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Abstract We present kinetic inductance measurements in current driven Josephson junction arrays. Measurements performed with circular coils indicate that this technique is very sensitive to the vortex mobility. Results obtained with anisotropic detection coils provide experimental evidence for the anisotropic response of a driven vortex lattice. Anisotropic behavior is obtained when rising the temperature or the mean vortex velocity as indicated by the loss of the superconducting shielding capability, first in the direction of vortex motion and then in the perpendicular direction.
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Call Number BT @ hernan @ shalom03 Serial 42
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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 1994 Publication (up) 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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ISSN 0038-1098 ISBN Medium
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Notes ISI:A1994MX74400003 Approved no
Call Number BT @ hernan @ Serial 107
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Author Huber, J.G.; Bulman, J.B.; Sereni, J.G.
Title Superconductivity under pressure and low temperature specific heat of ThPr alloys Type Journal Article
Year 1982 Publication (up) Solid State Communications Abbreviated Journal Solid State Commun.
Volume 43 Issue 12 Pages 925-931
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Abstract Measurements of superconducting transition temperature under pressure and low temperature specific heat are presented for ThPr alloys. At 18.2 kbar the normal- to superconducting-state phase boundary extends beyond 50 at.% Pr. This system is discussed in terms of a non-magnetic singlet ground state for the Pr3+ ions due to crystal field splitting. A splitting scheme which varies with Pr concentration is proposed.
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Notes ISI:A1982PG48200012 Approved no
Call Number BT @ hernan @ Serial 134
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Author Sereni, J.G.; Huber, T.E.; Luengo, C.A.
Title Low temperature specific heat of Th-Gd spin glass Type Journal Article
Year 1979 Publication (up) Solid State Communications Abbreviated Journal Solid State Commun.
Volume 29 Issue 9 Pages 671-673
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Abstract The specific heat measurements of Th---Gd alloys, with Gd concentration ranging from 0.15% to 10.8% and temperatures between 0.4 and 8 K, are reported. The characteristic spin glass specific heat enhancement and its maximum was found linearly proportional to Gd concentration. At low temperatures a T2 dependence of the specific heat was observed and the entropy associated with the magnetic ordering was the 70% of the expected value for the spin S = 7/2.
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Notes ISI:A1979GP96400009 Approved no
Call Number BT @ hernan @ Serial 139
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Author Sereni, J.G.; Huber, J.G.; Luengo, C.A.; Maple, M.B.
Title Specific heat of superconducting Th, Sc and Th, Y alloys with Ce Type Journal Article
Year 1975 Publication (up) Solid State Communications Abbreviated Journal Solid State Commun.
Volume 17 Issue 12 Pages 1581-1583
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Abstract Measurements of the specific heat jump ΔC at the superconducting critical temperature Tc on (Image )Ce and (Image )Ce Ce impurity, solid solution alloy systems indicate that the former systems obey the BCS law of corresponding states (LCS) characteristic of superconductors with non-magnetic impurities while the latter systems present deviations from the LCS linear relation between reduced parameters which are attributed to the development of localized moments at the Ce ions as the Y concentration increases.
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Notes ISI:A1975AZ36600027 Approved no
Call Number BT @ hernan @ Serial 141
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Author Luengo, C.A.; Huber, J.G.; Sereni, J.G.; Sweedler, A.R.; Cotignola, J.M.; Maple, M.B.
Title Low temperature specific heat of ThU Type Journal Article
Year 1972 Publication (up) Solid State Communications Abbreviated Journal Solid State Commun.
Volume 10 Issue 5 Pages 459
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Abstract The low temperature specific heat of the weakly magnetic system Image U has been measured in both the normal and superconducting states. U impurities are found to enhanve the normal state electronic specific heat coefficient γ at an unusually large rate of 4.85 ± 0.50 mJ/mole °K2 at. % U. The specific heat jump at the superconducting transition for an alloy of composition 0.075 at. % U follows the BCS law of corresponding states suggesting that the system Image U is essentially non-magnetic at superconducting temperatures.
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Notes ISI:A1972L797500015 Approved no
Call Number BT @ hernan @ Serial 142
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Author Núñez Regueiro, M.; Izbizky, M.A.; Esquinazi, P.
Title Thermal conductivity and “disorder” in high temperature superconductors Type Journal Article
Year 1988 Publication (up) 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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Notes Approved no
Call Number BT @ pedrazp @ Serial 583
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