Superconductivity and disorder enhancement in YBa2Cu3OyAx (A = F, Cl) compounds

J. Dehmej , Youssef Fouad , A. Raboutou , P. Peyral , C. Lebeau , J. Rosenblatt , Jean-Philippe Burin , P. Massiot , C. Perrin

The real and imaginary parts of the susceptibility at very low fields of halogenated YBCO ceramics have distinct onsets at temperatures Ts and Tc, respectively. We show that Ts is related to the average composition while Tc is sensitive to microscopic disorder. Thus Ts of YBa2Cu3OyAx coincides with the transition temperature of YBa2Cu3Oy+Cx, where the "doping power" 2C = −1, 1, 2, 3, for A = H, F, O, Cl, respectively. We discuss a mechanism for creation of disorder in the superconducting properties through an effective repulsive electrostatic interaction between halogen ions and oxygen vacancies. This mechanism describes the observed trends in Tcs and transition widths, even when one assumes that intergranular barriers play a minor role.

Mots clés: A. high-Tc superconductors; D. thermodynamic properties; D. disorder effects

Domaines: Supraconductivité [cond-mat.supr-con]

J. Dehmej, Youssef Fouad, A. Raboutou, P. Peyral, C. Lebeau, et al.. Superconductivity and disorder enhancement in YBa2Cu3OyAx (A = F, Cl) compounds. Solid State Communications, 1997, 102 (4), pp.335-340. ⟨10.1016/S0038-1098(96)00778-8⟩. ⟨hal-00511791⟩