Influence of Sr doping on twin-wall structure and flux pinning ofYBa2Cu3O

Anisotropic irreversibility of the Abrikosov and Josephson flux dynamics inYBa2−xSrxVieira1, Schaf2 2002Phys. Rev. B232120View full textAdd to dashboardCite

“…%) of Ba by Sr in the precursor oxides and carbonates of YBaCuO was found by electron microscopy 29 to result in substitutional Sr impurities at the Ba site. But this doping also gives rise to a high density of very tiny Sr precipitates within the crystal lattice.…”

Granular superconductivity in YBa2Cu3O7−δ single crystals by divalent impurities doping: Possible role of valence and orbital symmetry

“…The data however do not seem to indicate that the simple distribution of the impurities in the crystal lattice alone is the cause of granularity, moreover as granularity also develops in pure YBa 2 Cu 3 O 7Àd single crystals [1,2]. In some cases there is strong indication that specific attributes of the impurity atoms like valence, orbital symmetry or ion size play an important role too [3][4][5].With the aim of obtaining information about the origin of superconducting granularity in YBa 2 Cu 3 O 7Àd single crystals and to ascertain the role of the valence and the orbital symmetry of the impurity atoms in the induction of superconducting granularity, we investigate the effects of the divalent Ca atoms at the Y site, the divalent Sr atoms at the Ba site and the divalent Zn atoms at the Cu site on the magnetic irreversibility and the magnetoresistive transition of these doped YBa 2 Cu 3 O 7Àd single crystals. We compare the obtained results with those of a pure YBa 2 Cu 3 O 7Àd single crystal [5].…”

“…The effect of Sr at the Ba site of YBa 2 Cu 3 O 7Àd is rather moderate, but substitution of large proportions of Ba by Sr also leads to superconducting granularity [3,5,9]. The perturbation of Sr however is not via orbital symmetry breaking but via lattice distortion.…”

“…The data however do not seem to indicate that the simple distribution of the impurities in the crystal lattice alone is the cause of granularity, moreover as granularity also develops in pure YBa 2 Cu 3 O 7Àd single crystals [1,2]. In some cases there is strong indication that specific attributes of the impurity atoms like valence, orbital symmetry or ion size play an important role too [3][4][5].…”

“…The ionic radius of Sr is considerably smaller than that of Ba. Crystallographic studies [3] have shown that Sr locally pulls together the neighboring couples of the CuO 2 planes thereby introducing extensive distortion in the planar superconducting morphology.…”