|
|
Sereni, J. G., J. G. Huber, C. A. Luengo, and M. B. Maple. "Calorimetric study of the magnetization of Ce impurities in superconducting Th-Y and Th-Sc alloys." Journal of Low Temperature Physics 30, no. 5-6 (1978): 729–737.
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).
|
|
|
|
Guimpel, J., M. E. de la Cruz, F. de la Cruz, H. J. Fink, O. Laborde, and J. C. Villegier. "Size dependence of the Superconducting critical temperature and fields of Nb/Al multilayers." Journal of Low Temperature Physics 63, no. 1-2 (1986): 151–165.
Abstract: The critical temperatureT cof Nb/Al multilayers decreases as the total sample thicknessd Tis decreased while the thickness of each Nb and Al layer is kept constant. To understand this behavior, models based on the proximity effect and on weak two-dimensional (2D) localization are employed. The latter uses a characteristic length, the thermal diffusion length, in relation tod Tto obtain 2D behavior and leads to a reasonable explanation ofT c(d T). It is also found that the slope atT c(d T) of the critical magnetic field perpendicular to the layers is independent ofd Twhen the Nb and Al layer thicknesses are kept constant. The angular dependence of the critical field is also measured.
|
|
|
|
Trovarelli, O., J. G. Sereni, and J. P. Kappler. "Role of Ce sublattices in the thermal and magnetic properties of Ce7X3 (X=Ni, Ru, Rh, Ir, Pd, and Pt) compounds." Journal of Low Temperature Physics 108, no. 1-2 (1997): 53–85.
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.
|
|
|
|
Luzuriaga, J. "Measurements in the laminar and turbulent regime of superfluid4He by means of an oscillating sphere." Journal of Low Temperature Physics 108, no. 3-4 (1997): 267–277.
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.
|
|
|
|
Konstantinov, D., W. Homsi, J. Luzuriaga, C. - K. Su, M. A. Weilert, and H. J. Maris. "How Does a Bubble Chamber Work?" Journal of Low Temperature Physics 113, no. 3-4 (1998): 485–490.
Abstract: A charged particle passing through a bubble chamber produces a track of bubbles. The way in which these bubbles are produced has been a matter of some controversy. We consider the possibility that in helium and hydrogen bubble chambers the production of bubbles is primarily a mechanical process, rather than a thermal process as has often been assumed. The model we propose gives results which are in excellent agreement with experiment.
|
|
|
|
Cruz, F. de la, Y. Fasano, M. D. Seta, M. Menghini, and H. Pastoriza. "Plastic and Elastic Symmetry Transformations Induced in the Vortex Lattice of Anisotropic and Layered Superconductors." Journal of Low Temperature Physics 135 (2004): 99–110.
Abstract: We make a comparative analysis of the response of the three-dimensional vortex lattice in Bi$2$Sr$2$CaCu$2Ο8$ and NbSe$2$ to the presence of square arrays of pinning sites localized at one extremity of the vortex crystals. The absence of the hexagonal to square symmetry transformation and the induction of a distorted hexagonal symmetry in the vortex lattice of NbSe$2$ contrast to the observed symmetry change in Bi$2$Sr$2$CaCu$2Ο8$. The dissimilar response in both cases is explained taking into account the vortex structure solidification mechanisms in both materials: The plastic response in the case of the layered material Bi$2$Sr$2$CaCu$2Ο8$ is suggested to be a result of the simultaneity of solidification and coupling of bidimensional pancake vortices whereas a viscous solidification is the responsible for the three-dimensional elastic response in NbSe$_2$.
|
|
|
|
Hernandez, A., O. Ares, C. Hart, D. Domínguez, H. Pastoriza, and A. Butera. "Dissipation in mesoscopic superconductors with ac magnetic fields." Journal of Low Temperature Physics 135 (2004): 119–122.
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
|
|
|
|
Marconi V. I., H. Pastoriza, and D. Domínguez. "Transverse voltage in disordered Josephson junction arrays with diagonal bias." Journal of Low Temperature Physics 135 (2004): 135–138.
Abstract: We study numerically the effect of disorder in the transport properties of square Josephson junction arrays with a dc current applied in the diagonal direction ([11] direction). We obtain a finite transverse voltage in this case when we consider the presence of disorder in the critical currents of the junctions. We show that this behavior is in good agreement with previous experimental, results in square arrays with a diagonal current drive.
|
|
|
|
Shalóm, D. E., and H. Pastoriza. "Experimental Method to Measure Anisotropic Transport in 2D Superconductors." Journal of Low Temperature Physics 135 (2004): 153–156.
Abstract: A two-coil kinetic inductance technique for measuring anisotropic response in two-dimensional (2D) superconductors is presented. Serpentine-shaped coils are lithographically patterned directly on top of the sample, separated by isolation layers. The drive and receive coils are positioned in a way that enhances signal from longitudinal currents and reduces transversal ones, maximizing the ratio. Anisotropic transport can be directly measured with this technique, even when anisotropy is induced by the transport current.
|
|
|
|
Pedrazzini, P., M. G. Berisso, O. Trovarelli, J. G. Sereni, and C. Geibel. "Evolution of the ground state in the ternary system CeT2Si2 (T=Cu, Rh and Pd)." Journal of Low Temperature Physics 135, no. 1-2 (2004): 143–146.
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.
|
|
