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Author (up) Rodriguez, D.S.; Rodriguez, E.; Luzuriaga, J.; Waszczak, J.V.; Cheong, S.W. doi  openurl
  Title Role of anisotropy in the vortex lattice of superconductors high-Q oscillator measurements in 2H-NbSe2 and La1.825Sr.075CuO4 Type Journal Article
  Year 1994 Publication Physica C Abbreviated Journal  
  Volume 229 Issue 1-2 Pages 59-64  
  Keywords  
  Abstract Measurements of the response of the flux-line lattice in NbSe2 and La1.825Sr0.075CuO4 show important differences between these two materials. In particular, we have studied the magnetic-field and angular dependence of the response of a high-Q mechanical oscillator in fields of up to 1 T. The features seen in NbSe2 seem to be well explained in terms of a change in the pinning regime, usually termed the ''peak effect'' in the critical current, using the collective-pinning model of Larkin and Ovchivnikov within Ginzburg-Landau anisotropic theory. On the other hand the behavior found in the high-T(c) material LSCO seems to fall naturally into a description which takes into account the possibility of phase transitions in the vortex lattice and the quasi-two-dimensional character of the superconductivity.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0921-4534 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:A1994PF49500008 Approved no  
  Call Number BT @ hernan @ Serial 252  
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Author (up) Rodríguez, E.; Duran, C.; Luzuriaga, J.; de la Cruz, F.; Fainstein, C. doi  openurl
  Title Anomalous behaviour of the vortex structure in Bi4Ca2Sr4Cu4O16+y measured with a vibrating reed at low magnetic fields Type Journal Article
  Year 1990 Publication Physica C: Superconductivity Abbreviated Journal Physica C  
  Volume 165 Issue 3-4 Pages 315-320  
  Keywords  
  Abstract The response of the vortex structure in ceramic samples of Bi4Ca2Sr4Cu4O16+y has been measured by means of a vibrating reed technique in magnetic fields below 0.2 T. An anomally in the response of the reed is seen at temperatures of around 30 to 40 K, well below the critical temperature, indicating a transition similar to that attributed to a melting of the Flux Line Lattice. There is a shift in the temperature at which the anomaly is detected when one increases the driving force on the reed, while the dissipation shows a maximum associated to the transition which scales with the square of the applied magnetic field. Comparison with magnetization measurements shows that there is non-zero critical current at the same temperature where the anomalous behaviour is detected with our technique.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0921-4534 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:A1990CN49800014 Approved no  
  Call Number BT @ hernan @ Serial 261  
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Author (up) Rodriguez, E.; Luzuriaga, J.; Dovidio, C.A.; Esparza, D.A. url  openurl
  Title Softening of the flux-line structure in La1.8Sr0.2CuO4 measured by a vibrating reed Type Journal Article
  Year 1990 Publication Physical Review B Abbreviated Journal Phys. Rev. B  
  Volume 42 Issue 16 Pages 10796-10799  
  Keywords  
  Abstract Vibrating-reed measurements in La1.8Sr0.2CuO4 in a magnetic field show that the flux-line structure (FLS) becomes uncoupled from the material at a temperature TH of 23 K, much below the critical temperature of the sample, which is 32 K. The behavior is similar to that found in Bi2Sr2CaCu2O8 but shows some significant differences, the most important being that TH changes little with magnetic field throughout the measured field range (0.01 TH1 T). For low fields, TH is below the reversibility line of the magnetization. This seems to imply that the reversibility line and the line at which the FLS softens have to be considered as distinct physical phenomena. It is argued that neither flux-lattice melting nor giant flux creep considered separately can account for the data in a wholly satisfactory manner.  
  Address Centro Atmico Bariloche, (8400) Bariloche, Argentina  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 01631829 (ISSN) ISBN Medium  
  Area Expedition Conference  
  Notes Cited By (since 1996): 2; Export Date: 28 April 2009; Source: Scopus; doi: 10.1103/PhysRevB.42.10796; Language of Original Document: English; Correspondence Address: Rodrguez, E.; Centro Atmico Bariloche (8400) Bariloche, Argentina Approved no  
  Call Number BT @ luzuriag @ Serial 489  
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Author (up) Rodriguez, E.; Luzuriaga, J.; Núñez Regueiro, M.; Fainstein, C. doi  openurl
  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.  
  Address  
  Corporate Author Thesis  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0038-1098 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:A1991FA71400006 Approved no  
  Call Number BT @ hernan @ Serial 256  
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Author (up) Safar, H.; Durán, C.; Guimpel, J.; Civale, L.; Luzuriaga, J.; Rodríguez, E.; de la Cruz, F.; Fainstein, C.; Schneemeyer, L.F.; Waszczak, J.V. url  doi
openurl 
  Title Logarithmic to nonlogarithmic flux creep transition and magnetic flux hardening in BiSrCaCuO superconducting ceramics Type Journal Article
  Year 1989 Publication Physica C: Superconductivity Abbreviated Journal  
  Volume 162-164, Part 1 Issue Pages 665-666  
  Keywords  
  Abstract A sharp temperature and field dependent transition from a logarithmic to a non-logarithmic flux creep behavior has been found in BiSrCaCuO superconductors. The transition is not followed by any noticeable change in the magnetization. However, vibrating reed measurements show that it coincides with a strong hardening of the magnetic structure. The transition occurs at fields and temperatures well below the reversibility line. The possible relation to the recently proposed flux lattice melting is discussed.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0921-4534 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ jguimpel @ Serial 626  
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Author (up) Safar, H.; Durán, C.; Guimpel, J.; Civale, L.; Luzuriaga, J.; Rodriguez, E.; de la Cruz, F.; Fainstein, C.; Schneemeyer, L.F.; Waszczak, J.V. url  doi
openurl 
  Title Logarithmic-to-nonlogarithmic flux-creep transition and magnetic-flux hardening in Bi-Sr-Ca-Cu-O superconducting ceramics Type Journal Article
  Year 1989 Publication Physical Review B Abbreviated Journal Phys. Rev. B  
  Volume 40 Issue 10 Pages 7380  
  Keywords  
  Abstract A sharp temperature- and field-dependent transition from a logarithmic to a nonlogarithmic flux-creep behavior has been found in Bi-Sr-Ca-Cu-O superconductors. The transition is not followed by any noticeable change in the magnetization. However, vibrating-reed measurements show that it coincides with a strong hardening of the magnetic structure. The transition occurs at fields and temperatures well below the reversibility line. The possible relation to the recently proposed flux lattice melting is discussed.  
  Address  
  Corporate Author Thesis  
  Publisher American Physical Society Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ jguimpel @ 10.1103/PhysRevB.40.7380 Serial 627  
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Author (up) Schmoranzer, D.; Jackson, M.J.; Luzuriaga, J. doi  openurl
  Title On the Non-linear Damping of Mechanical Oscillators in Flows of 4He Type Journal Article
  Year 2014 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.  
  Volume 175 Issue 1 Pages 97-103  
  Keywords Resonator; Non-linear dissipation; Turbulence; Liquid helium  
  Abstract In the studies of both classical and quantum turbulence, significant attention is devoted to the investigation of the behavior of various submerged resonators. Upon entering the turbulent regime, the oscillators start to experience a significant drag force, which varies non-linearly with velocity. We present an empirical way of modeling such systems, and calculate the expected resonant response of such oscillators near the fundamental frequency as a function of the applied driving force. We apply the model to the crossover from linear to non-linear drag forces and compare with previous models as well as selected experimental data on the transition to turbulence in oscillatory flow of 4He.  
  Address  
  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 663  
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Author (up) Zemma, E.; Luzuriaga, J. doi  openurl
  Title 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.  
  Address  
  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 661  
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Author (up) Zemma, E.; Luzuriaga, J. doi  openurl
  Title Turbulent Flow Around an Oscillating Body in Superfluid Helium: Dissipation Characteristics of the Nonlinear Regime Type Journal Article
  Year 2013 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.  
  Volume 172 Issue 3-4 Pages 256-265  
  Keywords Quantum fluids; Turbulence; Superfluid helium; Nonlinear oscillator; Vibrating paddle; Critical velocity  
  Abstract By examining the resonance curves of an oscillator submerged in superfluid liquid helium, it is found that their shape is affected by two distinct dissipation regimes when the amplitude is large enough to generate turbulence in the liquid. In a resonance curve, the central part close to resonance, may be in a turbulent regime, but the response is of much lower amplitude away from the resonance frequency, so that the oscillation can still be in the linear regime for frequencies not exactly at resonance. This introduces an ambiguity in estimating the inverse quality factor Q −1 of the oscillator. By analyzing experimental data we consider a way of matching the two ways of estimating Q −1 and use the information to evaluate the frictional force as a function of velocity in a silicon paddle oscillator generating turbulence in the superfluid.  
  Address  
  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 662  
Permanent link to this record
 

 
Author (up) Zemma, E.; Luzuriaga, J. doi  openurl
  Title Measurements of Turbulence Onset and Dissipation in Superfluid Helium with a Silicon Double Paddle Oscillator Type Journal Article
  Year 2012 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.  
  Volume 166 Issue 3-4 Pages 171-181  
  Keywords  
  Abstract We have studied experimentally the response of a silicon single crystal double paddle oscillator submerged in superfluid helium from the lambda point to 1.55 K. Measuring the resonance frequency and dissipation on three modes of this high Q system allows us to study the dissipation at the onset of turbulence in the flow around the paddle. The critical velocity V c for turbulence onset decreases with temperature. If we use the density of the normal component of the superfluid to obtain a Reynolds number Re associated with V c we find a value which is largely temperature independent. This result is different from the behavior previously found by other authors below 1 K, where the quantized vorticity (extrinsic nucleation) is observed at velocities more than an order of magnitude greater. In our temperature range, we conclude that the transition is governed by the normal fraction acting as a classical fluid. The laminar regime shows a dissipation that is proportional to the viscous drag calculated by well known formulas for an object oscillating in a liquid. We also find a decrease in resonance frequency in the turbulent regime which is clearly observed but hard to reproduce from run to run.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1573-7357 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ hernan @ Serial 648  
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