A brief survey is made of the numerous anelastic relaxation processes with activation energies below 0.2 eV, which are found in the oxide superconductors with the 123 and 214 structure. Up to now there is no general agreement on their mechanisms, although some kind of electronic relaxation is often invoked. New measurements are presented of the process with the lowest activation energy, ~80 meV, in superconducting YBa2Cu3O6+x. It is shown that the intensity of this peak is maximum at the maximum oxygen stoichiometry, x = 1, and steeply decreases in the restricted range 0.9 < × < 1, disappearing below it. It is proposed that the anelastic relaxation is caused by the reorientation of pairs of the pz holes, which are observed at x > 0.8 by X-ray absorption spectroscopy.
Low activation energy relaxations in oxide superconductors
F Cordero;
1996
Abstract
A brief survey is made of the numerous anelastic relaxation processes with activation energies below 0.2 eV, which are found in the oxide superconductors with the 123 and 214 structure. Up to now there is no general agreement on their mechanisms, although some kind of electronic relaxation is often invoked. New measurements are presented of the process with the lowest activation energy, ~80 meV, in superconducting YBa2Cu3O6+x. It is shown that the intensity of this peak is maximum at the maximum oxygen stoichiometry, x = 1, and steeply decreases in the restricted range 0.9 < × < 1, disappearing below it. It is proposed that the anelastic relaxation is caused by the reorientation of pairs of the pz holes, which are observed at x > 0.8 by X-ray absorption spectroscopy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
