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Author Zemma, E.; Luzuriaga, J.
Title (up) Anomalous Trajectories of H2 Solid Particles Observed Near a Sphere Oscillating in Superfluid Turbulent 4He Type Journal Article
Year 2013 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 173 Issue 1-2 Pages 71-79
Keywords Quantum fluids; Turbulence; Superfluid helium; Flow visualization; Oscillating sphere
Abstract Using a relatively low cost apparatus, consisting of a glass dewar and a digital camera capable of taking images at 240 frames per second we have observed trajectories of frozen H2 particles which follow the flow of liquid helium below 2 K, around a sphere oscillating at 38 Hz. In some of the images the motion is compatible with laminar flow, while at high amplitudes, where we can reach Reynolds numbers of a few thousand in the normal component, the flow is clearly turbulent. In some of the videos taken we find particles being suddenly accelerated to several times the velocity of the oscillating sphere.
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Publisher Springer US Place of Publication Editor
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ISSN 0022-2291 ISBN Medium
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Notes Approved no
Call Number BT @ pedrazp @ Serial 661
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Author Maiorov, B.; Osquiguil, E.
Title (up) Bose-glass-like phases in oriented-twin YBa2Cu3O7-? crystals Type Journal Article
Year 2004 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 135 Issue 1-2 Pages 131-134
Keywords Low temperature effects; Magnetic fields; Superconducting materials; Bose-glass phases; Planar random defect array; Yttrium barium copper oxides; physics
Abstract We experimentally study the dynamical response of the superconducting vortex system near the solid-liquid transition by applying forces parallel and perpendicular to a planar random defect array. Our results show that for magnetic fields above a certain critical field Hcr'? 4 T the solid glassy vortex phase in YBa2Cu3O7-? crystals with oriented twin planes does not correspond to the so-called Bose-glass phase.
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Notes Cited By (since 1996): 1; Export Date: 17 April 2009; Source: Scopus; CODEN: JLTPA; Language of Original Document: English; Correspondence Address: Maiorov, B.; Superconductivity Technology Center; Los Alamos Laboratory Los Alamos, NM 87545, United States; References: Crabtree, G., Nelson, D.R., (1997) Phys. Today, 50, p. 38. , and references therein; Nelson, D.R., Vinokur, V.M., (1993) Phys. Rev. Lett., 68, p. 2398. , J. Lidmar and M. Wallin, Europhys. Lett. 47, 494 (1999); Grigera, S.A., (1998) Phys. Rev. Lett., 81, p. 2348; Maiorov, B., Osquiguil, E., (2001) Phys. Rev. B, 64, p. 052511; Maiorov, B., Nieva, G., Osquiguil, E., (2000) Phys. Rev. B., 61, p. 12427; Grigera, S.A., (2001) Phys. Rev. B., 63, p. 212509 Approved no
Call Number BT @ osquigui @ Serial 367
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Author Sereni, J.G.; Huber, J.G.; Luengo, C.A.; Maple, M.B.
Title (up) Calorimetric study of the magnetization of Ce impurities in superconducting Th-Y and Th-Sc alloys Type Journal Article
Year 1978 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 30 Issue 5-6 Pages 729-737
Keywords
Abstract Specific heat measurements are reported in detail for the Ce impurity in the superconducting matrix systems Th65Sc35Ce, Th80Y20Ce, and Th65Y35Ce. The variation of the specific heat jump DeltaC at the superconducting transition temperature T c is indicative of the magnetic nature of an impurity. For Th65Y35Ce a departure is found from the BCS law of corresponding states predicted for a nonmagnetic impurity. This departure is correlated with that observed for (La, Th)Ce systems and related to DeltaT c/n (initial slope of T c vs. n) and Ce effective size (implied by lattice parameter data).
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ISSN 0022-2291 ISBN Medium
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Notes ISI:A1978EW47300012 Approved no
Call Number BT @ hernan @ Serial 140
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Author Hernandez,A.; Ares,O.; Hart, C.; Domínguez,D.; Pastoriza,H.; Butera, A.
Title (up) Dissipation in mesoscopic superconductors with ac magnetic fields Type Journal Article
Year 2004 Publication Journal of Low Temperature Physics Abbreviated Journal
Volume 135 Issue Pages 119-122
Keywords
Abstract The response of mesoscopic superconductors to an ac magnetic field is investigated both experimentally

and with numerical simulations. We study small square samples with dimensions of the order of the penetration depth.

We obtain the ac susceptibitity $\chi=\chi'+\chi“$ at microwave frequencies as a function of the dc magnetic field

$H{dc}$. We find that the dissipation, given by $\chi”$, has a non monotonous behavior in mesoscopic samples.

In the numerical simulations we obtain that the dissipation increases before the penetration of vortices and

then it decreases abruptly after vortices have entered, the sample. This is verified experimentally, where we

find that $\chi"$ has strong oscillations as a function of $H
{dc}$ in small squares of Pb
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Call Number BT @ hernan @ hernandez04 Serial 24
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Author Schmoranzer, D., Jackson,M., Zemma, E., Luzuriaga,J.
Title (up) Double-Paddle Oscillators as Probes of Quantum Turbulence in the Zero Temperature Limit Type Journal Article
Year 2016 Publication Journal of Low Temperature Physics Abbreviated Journal
Volume 185 Issue Pages
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Call Number BT @ pedrazp @ Serial 745
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Author Dolz, M.I.; Pedrazzini, P.; Pastoriza, H.; Konczykowski, M.; Fasano, Y.
Title (up) Effect of Quenched Disorder in the Entropy-Jump at the First-Order Vortex Phase Transition of Bi{2}Sr{2}CaCu{2}O{8 + \delta } Type Journal Article
Year 2015 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 179 Issue 1-2 Pages 28-34
Keywords High Tc superconductors; First order vortex phase transition; Quenched disorder
Abstract We study the effect of quenched disorder in the thermodynamic magnitudes entailed in the first-order vortex phase transition of the extremely layered Bi 2 Sr 2 CaCu 2 O 8+δ compound. We track the temperature-evolution of the enthalpy and the entropy jump at the vortex solidification transition by means of AC local magnetic measurements. Quenched disorder is introduced to the pristine samples by means of heavy-ion irradiation with Pb and Xe producing a random columnar-track pins distribution with different densities (matching field BΦ ). In contrast with previous magneto-optical reports, we find that the first-order phase transition persists for samples with BΦ up to 100 Gauss. For very low densities of quenched disorder (pristine samples), the evolution of the thermodynamic properties can be satisfactorily explained considering a negligible effect of pinning and only electromagnetic coupling between pancake vortices lying in adjacent CuO planes. This description is not satisfactory on increasing magnitude of quenched disorder.
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Corporate Author Thesis
Publisher Springer US Place of Publication Editor
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 Approved no
Call Number BT @ pedrazp @ Serial 707
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Author Sereni, J.G.
Title (up) Entropy Bottlenecks at T->0 in Ce-Lattice and Related Compounds Type Journal Article
Year 2015 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 179 Issue 1-2 Pages 126-137
Keywords Heavy fermions; Specific heat anomalies; Entropy
Abstract A number of specific heat Cm anomalies are reported in Ce- and Yb-lattice compounds around 1 K which cannot be associated to usual phase transitions despite of their robust magnetic moments. Instead of a Cm(T) jump, these anomalies show coincident morphology: (i) a significant tail in Cm/T , with similar power law decay above their maxima ( T>Tm ), (ii) whereas a Cm(T2) dependence is observed below Tm . (iii) The comparison of their respective entropy gain Sm(T) indicates that ≈0.7R ln2 is condensed within the T>Tm tail, in coincidence with an exemplary spin-ice compound. Such amount of entropy arises from a significant increase of the density of low energy excitations, reflected in a divergent Cm(T>Tm)/T dependence. (iv) Many of their lattice structures present conditions for magnetic frustration. The origin of these anomalies can be attributed to an interplay between the divergent density of magnetic excitations at T→0 and the limited amount of degrees of freedom: Sm = R ln2 for a doublet-ground state. Due to this “entropy bottleneck,” the paramagnetic minimum of energy blurs out and the system slides into an alternative minimum through a continuous transition. A relevant observation in these very heavy fermion systems is the possible existence of an upper limit for Cm/TLimT→0 ≈7 J/mol K 2 observed in four Yb- and Pr-based compounds.
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Publisher Springer US Place of Publication Editor
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ISSN 0022-2291 ISBN Medium
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Notes Approved no
Call Number BT @ pedrazp @ Serial 709
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Author Sereni, J.G.
Title (up) Entropy Constraints in the Ground State Formation of Magnetically Frustrated Systems Type Journal Article
Year 2017 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 190 Issue 1-2 Pages 1-19
Keywords
Abstract A systematic modification of the entropy trajectory (Sm(T)) is observed at very low temperature in magnetically frustrated systems as a consequence of the constraint (Sm≥0) imposed by the Nernst postulate. The lack of magnetic order allows to explore and compare new thermodynamic properties by tracing the specific heat (Cm) behavior down to the sub-Kelvin range. Some of the most relevant findings are: (i) a common Cm/T|T→0≈7 J/mol K2 ‘plateau’ in at least five Yb-based very-heavy-fermions (VHF) compounds; (ii) quantitative and qualitative differences between VHF and standard non-Fermi-liquids; (iii) entropy bottlenecks governing the change of Sm(T) trajectories in a continuous transition into alternative ground states. A comparative analysis of Sm(T→0) dependencies is performed in compounds suitable for adiabatic demagnetization processes according to their ∂2Sm/∂T2 derivatives.
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Notes Approved no
Call Number BT @ pedrazp @ Serial 776
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Author Betancourth, D.; Correa, V.F.; García, D.J.
Title (up) Evidence of a Low Energy Anisotropy in GdCoIn_5 Type Journal Article
Year 2015 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 179 Issue 1-2 Pages 90-93
Keywords Rare earth magnetism; Antiferromagnetic transition; Anisotropy
Abstract We investigate the effects of an applied magnetic field on the magnetic properties of the antiferromagnet GdCoIn 5 . The prominent anisotropy observed in the susceptibility below TN is rapidly suppressed by a field of just a few Tesla. Further evidence of this low energy-scale is obtained from magnetoresistance and magnetostriction experiments. The lattice length, particularly, shows a sudden change below 2 T when the magnetic field is applied perpendicular to the crystallographic c^ -axis.
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Publisher Springer US Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN 0022-2291 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 710
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Author Pedrazzini, P.; Berisso, M.G.; Trovarelli, O.; Sereni, J.G.; Geibel, C.
Title (up) Evolution of the ground state in the ternary system CeT2Si2 (T=Cu, Rh and Pd) Type Journal Article
Year 2004 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 135 Issue 1-2 Pages 143-146
Keywords
Abstract The heavy fermion compounds CeCu2Si2, CeRh2Si2 and CePd2Si2 have been intensively investigated due to the non-conventional relation between superconductivity and magnetism. We have studied these compounds as constituents of a ternary system, where the Ce(RhxCu1-x)(2)Si-2, Ce(PdyRh1-y)(2)Si-2 and Ce(CuzPd1-z)(2)Si-2 alloys span the sides of a triangle with the respective stoichometric compounds at each vertex. In this article we discuss the evolution of the ground state throughout this ternary system, and we analyse (by means of the electrical resistivity) the influence of doping-induced disorder on the Kondo and magnetic ordering temperatures.
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Notes ISI:000189139000019 Approved no
Call Number BT @ hernan @ Serial 66
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