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Author Pasquini, G.; Levy, P.; Civale, L.; Nieva, G.; Lanza, H.
Title Linear response in the AC susceptibility of vortices in YBa2Cu3O7 crystals with columnar defects Type Journal Article
Year 1997 Publication Physica C: Superconductivity Abbreviated Journal
Volume (down) 274 Issue 1-2 Pages 165-172
Keywords
Abstract We explore the AC magnetic susceptibility of YBa2Cu3O7 single crystals with columnar defects. For vortices parallel to the defects the linear response is mainly determined by the Campbell penetration depth with a field independent Labusch parameter indicating that vortices are individually pinned. The small dissipation in this limit is likely to arise from thermal fluctuations of vortex segments between pairs of metastable states (two-level systems) in the Bose glass phase. Tilting vortices away from the tracks results in a reduction of the Bose glass temperature and an increase of the dissipation due to the reduction of the pinning forces. We discuss the onset of nonlinear response as the AC field increases.
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ISSN 0921-4534 ISBN Medium
Area Expedition Conference
Notes ISI:A1997WG88200021 Approved no
Call Number BT @ hernan @ Serial 243
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Author Fernandez, G.E.; Berisso, M.G.; Trovarelli, O.; Sereni, J.G.
Title Comparative study of the ferro-antiferromagnetic transition in Ce(Fe,Co)(2) and Ce(Fe,Al)(2) Type Journal Article
Year 1997 Publication Journal of Alloys and Compounds Abbreviated Journal J. Alloys Compd.
Volume (down) 261 Issue 1-2 Pages 26-31
Keywords
Abstract The magnetic, thermal and transport properties of Ce(Fe,Co)(2) and Ce(Fe,Al)(2) around the ferro-antiferromagnetic (F-AF) transition are studied and compared in their thermodynamic aspects. We confirm the presence of a structural contribution to the enthalpy of the transition in the case of Co substitution, which is the main difference between the AF phase transitions in both systems. The role of the Ce hybridization in the Co case and the ''canted'' nature of the AF phase in Ce(Fe,Al)(2) are discussed. (C) 1997 Elsevier Science S.A.
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ISSN 0925-8388 ISBN Medium
Area Expedition Conference
Notes ISI:A1997YE03600007 Approved no
Call Number BT @ hernan @ Serial 303
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Author Morré, E.; Grigera, S.; Osquiguil, E.; Nieva, G.; de la Cruz, F.
Title Angular restrictions on the glass transition and on the c-axis correlated liquid phase in twinned YBa2Cu3O7-? Type Journal Article
Year 1997 Publication Physics Letters A Abbreviated Journal Phys. Lett. A
Volume (down) 233 Issue 1-2 Pages 130-134
Keywords
Abstract We have measured the angular dependence of the vortex velocity correlation temperature Tth(H) in twinned YBa2Cu3O7-? single crystals. The data show that the c-axis correlated vortex liquid phase exists up to angles much larger than expected within a single vortex pinning picture. Despite this, the second-order solid-liquid glass transition is shown to be restricted only to external magnetic fields applied within a few degrees from the c-axis direction.
Address Centro Atómico Bariloche
Corporate Author Thesis
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ISSN 03759601 ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 13; Export Date: 17 April 2009; Source: Scopus; CODEN: PYLAA; Language of Original Document: English; Correspondence Address: Morr Approved no
Call Number BT @ osquigui @ Serial 381
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Author Sereni, J.G.; Geibel, C.; Berisso, M.G.; Hellmann, P.; Trovarelli, O.; Steglich, F.
Title Scaling of the ''C-p proportional to TlnT'' dependence in Ce systems Type Journal Article
Year 1997 Publication Physica B – Condensed Matter Abbreviated Journal Physica B
Volume (down) 230-232 Issue Pages 580-582
Keywords
Abstract We analyze the T ln T dependence of the specific heat (C-p) in several Ce binaries and ternaries. We find that these systems can be directly compared by using a scaling law of the type: C-p/t = -D log t + ET0, where t = T/T-0, with the scaling temperature T-0 similar to T-K, D = 7.2 J/(mol K) and 0 < E < 0.14 J/(mol K-2). This general function describes those systems within the 0.005 < t < 0.5 range and accounts for nearly 1/2 of the expected entropy of the Ce-doublet.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4526 ISBN Medium
Area Expedition Conference
Notes ISI:A1997WW40300168 Approved no
Call Number BT @ hernan @ Serial 93
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Author Kappler, J.P.; Besnus, M.J.; Haen, P.; Sereni, J.G.
Title Ce ground state in CePd1-xNix Type Journal Article
Year 1997 Publication Physica B: Condensed Matter Abbreviated Journal Physica B
Volume (down) 230-232 Issue Pages 162-164
Keywords
Abstract Alloying ferromagnetic CePd (Tc = 6.5 K) with the intermediate valence compound CeNi compresses the lattice, though the ferromagnetic order is present up to x = 0.94 in CePd1−xNix. We report here the competition of magnetic order and Kondo effect, through specific heat, magnetization and resistivity measurements. Detailed results gathered on the x = 0.95 sample show several features suggesting a non-Fermi liquid behaviour which may be due to the proximity to magnetic order: ϱ = ϱ0 + AT1.1 (3 < T ⩽ 30 K) and C/T ∝ − ln T(T ⩾ 0.9 K). At lower temperatures C/T tends to saturate at a value of 0.225 J/K2 mol, about three times the value observed for CeNi.
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Notes Approved no
Call Number BT @ pedrazp @ Serial 688
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Author Trovarelli, O.; Sereni, J.G.; Kappler, J.P.
Title Role of Ce sublattices in the thermal and magnetic properties of Ce7X3 (X=Ni, Ru, Rh, Ir, Pd, and Pt) compounds Type Journal Article
Year 1997 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low. Temp. Phys.
Volume (down) 108 Issue 1-2 Pages 53-85
Keywords
Abstract The role of the Ce sublattices in the thermal and magnetic properties of the Ce7X3 (X = Ni, Ru, Rh, Ir, Pd, and Pt) family of compounds is studied by means of ac and dc magnetic susceptibility, mngnetization and mainly specific-heat experiments in applied magnetic field. The experimental data show that in these compounds there is coexistence of magnetic order, heavy-fermion and intermediate-valence behavior, which is interpreted in terms of the contribution of the three different sublattices present in the crystalline structure of Th7Fe3-type (denoted by 1Ce(I), 3Ce(II) and 3Ce(III)). From the available volume of the Ce-III atoms in their crystallographic environment it is found that sublattice Ce-III has an intermediate-valence behavior, whereas from entropic considerations sublattices Ce-I and Ce-II are identified as responsible for the magnetic order or heavy-fermion behavior, depending on the Ce-ligand electronic structure. This systematics evidences a clear correlation between the thermal and magnetic properties of these compounds and the position of the respective Ce-ligands in the periodic table, through the particular sensitivity of Ce to the environmental conditions.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-2291 ISBN Medium
Area Expedition Conference
Notes ISI:A1997XK19200004 Approved no
Call Number BT @ hernan @ Serial 92
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Author Luzuriaga, J.
Title Measurements in the laminar and turbulent regime of superfluid4He by means of an oscillating sphere Type Journal Article
Year 1997 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume (down) 108 Issue 3-4 Pages 267-277
Keywords Calculations; Laminar flow; Oscillations; Spheres; Turbulence; Turbulent flow; Vibrations (mechanical); Oscillating sphere; Translational oscillation; Superfluid helium
Abstract The translational oscillations of a sphere in liquid helium have been measured as a way of studying superfluid turbulence. Experiments were carried out in the laminar flow regime for reference purposes, and good agreement found between measured and calculated quantities. In the turbulent region, the dissipation is found to be proportional to the square of the velocity of the sphere, as found previously by other workers. For high vibration amplitudes there is an increase in the hydrodynamic mass. This seems to scale with the superfluid fraction in a way that strongly suggests that the superfluid component plays an important role in the turbulent regime.
Address Comisi
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ISSN 00222291 (ISSN) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 2; Export Date: 28 April 2009; Source: Scopus; CODEN: JLTPA; Language of Original Document: English; Correspondence Address: Luzuriaga, J.; Comisi Approved no
Call Number BT @ luzuriag @ Serial 518
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Author Sereni, J.G.; Trovarelli, O.; Schmerber, G.; Kappler, J.P.
Title Comparative study of thermal and magnetic properties of CeTyX4-y ferromagnets Type Journal Article
Year 1997 Publication Physical Review B – Condensed Matter and Materials Physics Abbreviated Journal Phys. Rev. B
Volume (down) 56 Issue 9 Pages 5380-5386
Keywords
Abstract Low-temperature thermal (specific heat, C-P) and magnetic [ac susceptibility, chi(ac), and isothermal magnetization M(B)] measurements on CeTyX4-y ferromagnets (with T = Ni, Cu, Pd, Ag, Au, and X = Ga, Al, with 0.3 < y < 0.7) are reported. With the exception of T = Ni, all compounds with X = Ga show a typical second-order ferromagnetic transition. In the case of T = Ni, magnetic correlations set in at T approximate to 3T(C), (T-C being the Curie temperature) and the C-P(T) and chi(ac)(T) maxima (at 3.3 and 4.2 K, respectively) do not coincide, while the M(B) curves reveal an antiferromagnetic character at lower temperatures. In these systems, the magnetic entropy of the ordered phase is larger than 85% of Rln2, in coincidence with the low values of the Sommerfeld coefficient gamma less than or equal to 10 mJ/mol K-2. For T = Ag and X = Al, a strong diamagnetic signal was observed at T-s = 0.63 K in chi(ac)(T), with the characteristics of a superconducting component. The thermodynamical properties of these compounds confirm the lack of hybridization when the Ce atom is in a ferromagnetic ground state.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes ISI:A1997XW94200062 Approved no
Call Number BT @ hernan @ Serial 89
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Author Trovarelli, O.; Weiden, M.; MullerReisener, R.; GomezBerisso, M.; Gegenwart, P.; Deppe, M.; Geibel, C.; Sereni, J.G.; Steglich, F.
Title Evolution of magnetism and superconductivity in CeCu2(Si1-xGex)(2) Type Journal Article
Year 1997 Publication Physical Review B – Condensed Matter and Materials Physics Abbreviated Journal Phys. Rev. B
Volume (down) 56 Issue 2 Pages 678-685
Keywords
Abstract We have determined the magnetic phase diagram of CeCu2(Si1-xGex)(2) using specific heat, susceptibility, and resistivity measurements and additional thermal expansion and muon spin resonance experiments. The system evolves continuously from the heavy-fermion state at x = 0 to an antiferromagnetically (AF) ordered state at x = 1, though the magnetic structure undergoes significant modifications. The results strongly suggest that the AF ordering emerges from the A phase of pure CeCu2Si2. The phase diagram can be divided into three regions: Low Ge content (x less than or equal to 0.2) leads to an enhancement of the A phase of pure CeCu2Si2 and to a moderate decrease of the Kondo temperature. Despite this increase of the magnetic character, we could observe superconductivity up to x = 0.1. At large Ge content (x > 0.5) the behavior resembles that of pure CeCu2Ge2. The intermediate region is characterized by the appearance of a second magnetic transition below T-N, which seems to be of first-order type. The appearance of this transition leads to a well-defined critical point at x = 0.3 and suggests the possibility of another critical point at x = 0.5.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes ISI:A1997XL82700031 Approved no
Call Number BT @ hernan @ Serial 90
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Author Bauer, E.; Hauser, R.; Keller, L.; Fischer, P.; Trovarelli, O.; Sereni, J.G.; Rieger, J.J.; Stewart, G.R.
Title Onset of magnetic order in YbCu5-xAlx Type Journal Article
Year 1997 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume (down) 56 Issue 2 Pages 711-718
Keywords
Abstract Spectroscopic, magnetic, thermal, and transport measurements under pressure are presented which were performed on YbCu5-xAlx intermetallics. The substitution of Cu by Al in YbCu5 drives the system from an almost divalent behavior of the Yb ion in YbCu5 to a trivalent state in YbCu3Al2. A compensation between the normal thermal expansion and a valence-driven contraction was found for YbCu4Al. Antiferromagnetic order sets in for x>1.5, where an increasing Al content causes both a growing transition temperature and rising saturation moments reaching 2 K and about 2.1 mu(B), respectively, for x=2. At the critical concentration (x approximate to 1.5) the possibility of a non-Fermi-liquid state is analyzed together with its tuning by pressure.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes ISI:A1997XL82700035 Approved no
Call Number BT @ hernan @ Serial 91
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