Effects of Substituting Calcium for Yttrium on the Superconducting Properties of YBa2Cu3Oz Bulk Samples

We report systematic studies of AC magnetic susceptibility and transport properties of Y(1-x)Ca(x)Ba2Cu3Oz bulk samples with 0\leq x\leq 0.4. Single phase materials, reduction of carrier concentration and decrease of Tc to 85 K were obtained at doping levels up to 20%. For Y0.7Ca0.3Ba2Cu3Oz sample the improvement of grains boundary transport and screening capabilities has been observed as a result of the optimal ratio between carrier concentration and impurity phase BaCuO2 presence. The appearence of bulk pinning and nonlinear effects starting at the highest temperature were detected also.Comment: 12 pages, 8 figures, accepted in Physica

Muon-spin-rotation study of the effect of Zn substitution on magnetism in YBa2Cu3Ox

The magnetic properties of YBa2(Cu0.96Zn0.04)3Ox were studied in detail by means of muon spin rotation and relaxation for 6.0≤x≤6.92. The complete magnetic phase diagram was mapped out and a disordered magnetic state was found to persist between x=6.4 and x≃6.7 (metallic transition), in contrast with pure YBa2Cu3Ox. The appearance of this magnetic state is attributed to the effect of Zn on the doped hole dynamics and might be associated with the freezing of local moments due to Zn (6.43≤x≤6.88), which were also detected here, in the paramagnetic state

μSR Study of Zn-Substituted YBa2Cu3Ox

We report zero field and transverse field mgrSR. measurements in magnetic YBa2(Cu1–y Zn y )3O x . Mild disorder of the antiferromagnetic state (