Temperature dependence of the magnetic field penetration depth versus oxygen ordering in submicron YBCO particles

• Published in: Physica. C, Superconductivity Superconductivity, 1996-06, Vol.264 (3), p.295-304
• Main Authors: Fleisher, V.G., Laiho, R., Lähderanta, E., Stepanov, Yu.P., Traito, K.B.
• Format: Article
• Language: English
• Subjects: Glass state; Magnetization; Oxygen stoichiometry; Penetration depth; Structural phase transition
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/0921-4534(96)00283-3

The influence of oxygen ordering on the temperature dependence of the magnetic field penetration depth λ is investigated in submicron YBa 2Cu 3O 6+ x particles obtained by low-temperature ( T s = 800 − 850°C) synthesis from a sol-gel precursor. Additional OO bonds created at low temperature synthesis hinder the oxygen ordering in Cu(1)O plane despite of its high content ( x > 0.82). Oxygen exchange as well as additional annealing stimulate tetra-ortho transition and oxygen ordering. A wide linear range is observed in λ ab −2 ( T) for samples with highly disordered oxygen. This is attributed to strong phase fluctuations caused by local strains. A gauge-glass model with random distribution of order parameter phases describes the behavior of λ ab −2( T), revealed at initial stage of the hindered tetra-ortho transition. Transformation of the linear λ ab −2( T) fuction to a quadratic one with oxygen ordering is related to decreasing of local deformations and to transformation from a glass state to the usual superconducting orthophase. Two essentially different ways of oxygen ordering, reoxidation and additional annealing, result in the same final state with a similar power law of λ ab −2( T).