Paracoherence in polycrystalline La1.8Sr0.2CuO4-δ

LEVY, P.; ACHA, C.; BEKERIS, V.

SOLID STATE COMMUNICATIONS

PERGAMON-ELSEVIER SCIENCE LTD

Año: 1991 vol. 80 p. 849 - 853

0038-1098

We have studied the resistive transition into the superconducting state of single phase polycrystalline La1.8Sr0.2CuO4-δ samples, in a magnetic field range below 50 Oe. We find that at zero field and near the zero resistivity temperature the transition is well described as dissipation due to thermally induced phase fluctuations in neighbour superconducting grains. We find that the excess conductivity above the conductivity of the intergranular junctions displays critical behavior with unique critical exponent in four samples, independent of method of preparation, oxygen content and applied magnetic field; the obtained value, γ=2.0±0.1 differs from previously reported values for polycrystalline YBa2Cu3O7-y. In this description, increasing magnetic fields, enhance the granular behaviour of polycrystalline La1.8Sr0.2CuO4-δ as compared with previous results on samples with induced granularity. © 1991.