Braun, E., G. Jackel, B. Roden, J. G. Sereni, and D. Wohlleben. "Comparative study of the specific heat of superconducting and non-superconducting YBa2Cu3O7-x." Zeitschrift für Physik B Condensed Matter 72, no. 2 (1988): 169–173.
Abstract: We have measured the specific heat, the electrical resistance and the magnetic susceptibility of YBa2Cu3O7−x in a superconducting (sc) and in a non-superconducting (nsc) version. The latter was obtained by inducing a small loss of oxygen. In the sc sample we find a jump of the specific heat with ΔC=3.6 J mole−1 K−1. Below the maximum nearT c the specific heat of the sc version drops too fast for an electronic effect alone: there is a cross-over from excess to deficiency already at 0.9T c . The specific heat of the nsc version shows a change of slope in the temperature range between 70 and 80 K, which indicates the existence of a second specific heat anomaly, which apparently exists independently of that due to the onset of superconductivity and explains at least partially the premature crossover.
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KAPPLER, J. P., G. SCHMERBER, and J. G. SERENI. "CERIUM MAGNETIC-BEHAVIOR IN CE(PD,M) WITH M = CO, NI, RH, IR, PT, CU, AG AND AU." Journal of Magnetism and Magnetic Materials 76-7 (1988): 185–186.
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Osquiguil, E., L. Civale, R. Decca, H. Safar, E. Martinez, G. Nieva, and F. de la Cruz. "The Granular Behavior of LaSrCuO: Oxygen Concentration Effects on the Electrical Resistivity." In High Temperature Superconductors, Mat. Res. Soc. Symposium Proceedings, edited by K. Kitazawa and H. L. Tutler R. C. Dynes ed. M.B. Brosdky, 985. Vol. 99. Pittsburgh, PA: Mater. Res. Soc., 1988.
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Izbizky, M. A., M. Núñez Regueiro, P. Esquinazi, C. Durán, and C. Fainstein. "Phonon transport in superconducting EuBa2Cu3O7-x." Physics Letters A 129, no. 1 (1988): 71–75.
Abstract: We have measured the thermal conductivity, Young modulus sound velocity and internal friction of a polycrystalline sample of the ceramic superconductor EuBa2Cu3O7-x. The low temperature data can be quantitavely understood assuming the interaction of phonons with tunneling systems.
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Causa, M. T., S. M. Dutrus, C. Fainstein, G. Nieva, R. Sanchez, L. B. Steren, M. Tovar, R. Zysler, S. B. Oseroff, D. C. Vier et al. "Magnetic ordering in dilute GdxEu1−xBa2Cu3O7−δ superconductors." Physica C: Superconductivity 153 (1988): 188–189.
Abstract: We have measured the specific heat of GdxEu1−xBa2Cu3O7−δ (0 ≤ × ≤ 1). The data show a λ-type anomaly at high concentrations and a broad Schottky type anomaly at intermediate and low concentrations. We compare this behavior with theoretical predictions for a 2-dimensional Ising system.
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Núñez Regueiro, M., P. Esquinazi, M. A. Izbizky, C. Duran, D. Castello, J. Luzuriaga, and G. Nieva. "Evidence of tunneling systems through thermal and acoustic measurements in ceramic materials." Physica C: Superconductivity and its applications 153-155, no. PART 2 (1988): 1016–1017.
Abstract: We have neasured the sound velocity, internal friction, thermal conductivity and specific heat of La-based and (Y/Eu)- based ceramics. The low temperature data can be understood in terms of the Tunneling Model assuming the existence of Tunneling Systems (TS). From these measured properties we obtain values for the parameter C=P?2/?v2, where P is the density of states of TS, ? the coupling constant between phonons and TS, ? the mass density and v the sound velocity close to those obtained for amorphous and “orientational” disordered crystalline materials. Our data would indicate that the TS are intrinsic defects independent of the sample porosity.
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Esquinazi, P., and C. Durán. "Magnetization and pinning measurements with the vibrating Reed on high-Tc ceramics." Physica C: Superconductivity 153-155, no. Part 3 (1988): 1499–1500.
Abstract: By means of the vibrating reed technique we have measured the lower critical field and the elastic coupling of vortices to pinning centers in La-Sr-Cu-O and Eu-Cu-O ceramics.our results indicate that the diamagnetism probed by the reed and the pinning scaling behaviour depend on the amount of oxygen in the La-based ceramic. In the Eu-based sample the lower critical field has a highly anomalous temperature dependence.
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