Anomalous magnetic ordering in PrBa_2Cu_3O_{7-y} single crystals: Evidence for magnetic coupling between the Cu and Pr sublattices

In Al-free PrBa_2Cu_3O_{7-y} single crystals the kink in the temperature dependence of magnetic susceptibility chi_{ab}(T), connected with Pr antiferromagnetic ordering, disappears after field cooling (FC) in a field H || ab-plane. The kink in chi_c(T) remains unchanged after FC in H || c-axis. As a possible explanation, freezing of the Cu magnetic moments, lying in the ab-plane, caused by FC in H || ab, hinders their reorientation and, due to coupling between the Pr and Cu(2) sublattices, ordering of the Pr^{3+} moments. A field induced phase transition and a field dependence of the Pr^{3+} ordering temperature have been found for both H || c and H || ab.Comment: 11 pages (LaTex with elsart.sty), 5 EPS figs. Accepted to Physica

Study of the Y1-xErxBa2Cu3O7-δ system: Electrical resistivity measurements

In-plane electric conductivity of Y1-xErxBa2Cu3O7-δ single crystals with Er content x ranging from 0 to 0.48 have been measured as a function of temperature from 85 K to 300 K. The temperature dependencies of reduced resistance for all sample are identical suggesting that erbium substitution for yttrium does not produce sizable scattering of charge carriers