Civale L., and E. N. Martinez. "Linear temperature dependence of the resistivity in the new superconductors." Physical Review B 38, no. 1 (1988): 928–930.
Abstract: We present an elementary proof that, irrespective of dimensionality, the electrical resistivity of a simple conductor should be linear with temperature for T>2PFS / kB??D if PF?h? / a, where PF is the Fermi momentum, s the speed of sound, a the lattice constant, and ?D the Debye temperature.
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Kappler, J. P., P. Lehmann, G. Schmerber, G. Nieva, and J. G. Sereni. "Magnetic properties of the Ce-Rh binary phases." Journal de Physique Colloques 49, no. C8 (1988): 721–722.
Abstract: Crystallographic, magnetic and resistivity studies on the Ce-Rh binary phases clearly define two Ce ground state regions : i) CeRh3, CeRh2 and CeRh as intermediate valence compounds and ii) Ce5Rh4, Ce3Rh2 Ce5Rh3 and Ce7Rh3 with magnetic transitions at low temperature.
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Kappler, J. P., E. Beaurepaire, G. Krill, C. Godart, G. Nieva, and J. G. Sereni. "Magnetic to non-magnetic transition of Ce induced by volume in Ce(Pd, Ni) and electron concentration in Ce(Pd, Rh)." Journal de Physique Colloques 49, no. C-8 (1988): 723–724.
Abstract: Unit cell volume, magnetic properties and LIII X-ray absorption edge studies in Ce(Pd, M) with M = Ni or Rh show that the Ce demagnetization is mainly driven by volume reduction in Ce(Pd, Ni) and essentially due to the reduction of the d electron number in Ce(Pd, Rh).
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Kappler, J. P., G. Nieva, J. G. Sereni, and J. Souletie. "Static Scaling in the CePd3Bx Kondo system." Journal de Physique Colloques 49, no. C-8 (1988): 725–726.
Abstract: The static scaling hypothesis for continuous transitions, extended to cases where Tc < 0, has appropriate features to describe heavy fermions. We present here the application of this model to the specific-heat and susceptibility anomalies for the concentrated Kondo system CePd3Bx (x = 0.4 and 1).
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Osquiguil, E., R. Decca, G. Nieva, L. Civale, and F. de la Cruz. "La1.80 Sr0.20 CuO4-delta a clean limit superconductor." Solid State Communications 65, no. 6 (1988): 491–494.
Abstract: The electrical resistivity of the superconductor La1.80Sr0.20Cu04-? has been measured in a wide range of temperatures as a function of oxygen and vacuum heat treatments. The resistivity changes reversibly orders of magnitude with oxygen concentration. There is no sign of saturation at high temperatures, even for samples where the resistivity is increased by heat treatment in vacuum. Using the experimental data and general arguments it is concluded that the ceramic superconductors are high ? materials in the clean limit.
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Durán, C., P. Esquinazi, C. Fainstein, and M. Núñez Regueiro. "Anomalies in the internal friction and sound velocity in YBa2Cu3O7-x and EuBa2Cu3O7-x superconductors." Solid State Communications 65, no. 9 (1988): 957–961.
Abstract: Internal friction Q-1 and Young Modulus sound velocity vE measurements at 1 kHz in YBa2Cu3O7?x and EuBa2Cu3O7?x polycrystalline samples reveal anomalies at the superconducting transition and at not, vert, similar37 K. The anomaly in vE at not, vert, similar90 K is accompanied by an absorption peak and is in agreement with published ultrasonic measurements, suggesting a lattice deformation at the superconducting transition.
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Braun, E., A. Bürger, B. Roden, and J. G. Sereni. "Spin glass-like behaviour of the singlet ground state system: ThTb." Solid State Communications 66, no. 11 (1988): 1141–1144.
Abstract: We have studied the temperature and field dependence of the magnetic susceptibility, X, on the single-ground-state Th1?nTbn system, in the 0.2 < n < 0.6 concentration range. The characteristic maximum of a spin glass transition was found at a temperature Tg, which increases linearly with the impurity concentration. As expected, the maximum of X is reduced by the increment of the applied magnetic field. The spin glass order parameter, as well as its critical exponent were evaluated by using the Sherrington-Kirkpatrick theory.
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Núñez Regueiro, M., M. A. Izbizky, and P. Esquinazi. "Thermal conductivity and “disorder” in high temperature superconductors." Solid State Communications 67, no. 4 (1988): 401–404.
Abstract: We analyze the controversial thermal conductivity results on high temperature superconductors by scaling the data with material parameters to compare them to other materials with similar behaviour. We show that they have the same general features observed in amorphous and disordered crystalline materials. Possible origins of the disorder are discussed.
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NIEVA, G. L., J. G. SERENI, M. AFYOUNI, G. SCHMERBER, and J. P. KAPPLER. "FROM FERROMAGNETIC TO NON-MAGNETIC SINGLET GROUND-STATE IN CEPD1-XNIX." Zeitschrift für Physik B Condensed Matter 70, no. 2 (1988): 181–186.
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Braun, E., A. Bürger, G. L. Nieva, B. Roden, and J. G. Sereni. "Unexpected magnetic behaviour in a singlet crystal field ground state induced by Tb 4f-instability." Zeitschrift für Physik B Condensed Matter 70, no. 2 (1988): 187–192.
Abstract: The magnetic susceptibility (chi) of Th1-x Tb x alloys (with 5<x<55a/o Tb) in the range of 1 K<T<350K and the specific heat (forx=1.5a/o Tb) for 0.5<T<10 K were measured. A maximum in chi(T) was observed at a temperature which depends on concentration. The crystal field level scheme that fits the specific heat measurements shows two non-magnetic singlets as lowest levels. Such ambiguity is discussed within the framework of the 4f-Tb instability. The results are in agreement with the matrix superconductiveT c decrease. The contribution of the interconfigurational mixing on chi and the specific heat is also discussed.
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