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Author (up) R. H. Rodriguez, L. Tosi, M. Menghini, H. Pastoriza and C. A. Balseiro url  doi
openurl 
  Title Multiple First Order Transitions in Cr Thin Films Type Journal Article
  Year 2014 Publication Journal of Physics: Conference Series Abbreviated Journal  
  Volume 568 Issue 4 Pages 042031  
  Keywords  
  Abstract The incommensurate spin density wave (SDW) in metalic Cr forms below T N = 311K and is characterized by a temperature dependent wave-vector Q along the direction. The wavelength varies from 78 Ã… at 300 K to 60 Ã… at 150 K. In thin films, the Q-vector orients perpendicular to the film surface and the SDW is forced to satisfy boundary conditions. As a consequence of the confinement, the SDW wavelength is quantized in a set of available modes, each one having n nodes. As the temperature decreases the wavelength does not follow a continuous bulk-type variation but jumps between different allowed values. These jumps occur at certain determined temperatures T n as first order type transitions which are accompanied with a decrease ( n to n + 1 nodes) or an increase ( n + 1 to n nodes) of the resistance. In this work, we present transport measurements on Cr thin films showing hysteretic behavior in the resistance as a function of temperature in cooling-warming cycles. The hysteresis loops are thickness dependent and present structures which we associate with the possible multiple transitions that may occur as temperature is swept.  
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  ISSN 1742-6596 ISBN Medium  
  Area Expedition Conference Low Temperature Physics XXVII  
  Notes Approved no  
  Call Number BT @ hernan @ Serial 702  
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Author (up) Romero, M.A.; Aligia, A.A.; Sereni, J.G.; Nieva, G. url  doi
openurl 
  Title Interpretation of experimental results on Kondo systems with crystal field Type Journal Article
  Year 2014 Publication Journal of Physics: Condensed Matter Abbreviated Journal J. Phys. : Condens. Matter  
  Volume 26 Issue Pages 025602  
  Keywords cond-mat.str-el  
  Abstract We present a simple approach to calculate the thermodynamic properties of single Kondo impurities including orbital degeneracy and crystal field effects (CFE) by extending a previous proposal by K. D. Schotte and U. Schotte [Physics Lett. A 55, 38 (1975)]. Comparison with exact solutions for the specific heat of a quartet ground state split into two doublets shows deviations below $10\%$ in absence of CFE and a quantitative agreement for moderate or large CFE. As an application, we fit the measured specific heat of the compounds CeCu$2$Ge$2$, CePd${3}$Si${0.3}$, CePdAl, CePt, Yb$2$Pd$2$Sn and YbCo$2$Zn${20}$. The agreement between theory and experiment is very good or excellent depending on the compound, except at very low temperatures due to the presence of magnetic correlations (not accounted in the model).  
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  Notes arXiv:1308.3256v3; Journal Ref: J. Phys.: Condens. Matter 26 (2014) 025602 (9pp) Approved no  
  Call Number BT @ berisso @ Serial 675  
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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.  
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  Publisher Springer US Place of Publication Editor  
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  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) Sereni, J.G.; Gomez Berisso, M.; Betancourth, D.; Correa, V.F.; Canales, N.C.; Geibel, C. url  doi
openurl 
  Title Evidence for a dimensionality crossover at the disappearance of magnetism in the Kondo lattice alloy CeCo1-xFexSi Type Journal Article
  Year 2014 Publication Physical Review B Abbreviated Journal Phys. Rev. B  
  Volume 89 Issue 3 Pages 035107  
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  Publisher American Physical Society Place of Publication Editor  
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  Notes Approved no  
  Call Number BT @ berisso @ 10.1103/PhysRevB.89.035107 Serial 677  
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Author (up) Zemma, E.; Luzuriaga, J.; Babuin, S. url  doi
openurl 
  Title Analysis of motion of solid hydrogen tracer particles in oscillating superfluid flows Type Conference Article
  Year 2014 Publication Journal of Physics: Conference Series Abbreviated Journal J. Phys.: Conf. Ser.  
  Volume 568 Issue Pages 012029  
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  Abstract We have developed a relatively simple cryostat which allows us to image turbulent flows in superfluid helium at temperatures below 2 K, using frozen H2 particles. We analyze the statistics of the velocities of these solid tracers, which follow the turbulent flow generated by oscillating bodies. We have also studied one of the oscillators working in air at room temperature, and traced the flow with solid talcum particles for comparison. Images were recorded by a digital camera at 240 frames per second, while frequencies of the oscillators are between 20 to 45 Hz. The flow is characterized by a modified Reynolds number Reδ based on the viscous penetration depth δ. Software in a dedicated particle tracking velocimetry code allows us to compute the trajectories and velocities of tens of thousands of particles. We have obtained the number of particles for equally spaced intervals of the velocity modulus. For the oscillators in the superfluid, the probability of finding particles at higher velocities has an exponential decay. Within our resolution the statistics in the superfluid for oscillating objects with sharp borders is largely independent of Reδ, while the logarithmic decay at low velocities seems faster than for high velocities for rounded objects. On the other hand, for data taken in air the result is closer to a classical Gaussian distribution of velocities.  
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  Area Expedition Conference 27th International Conference on Low Temperature Physics (LT27)  
  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 735  
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