J. Phys. I France
Volume 3, Numéro 7, July 1993
Page(s) 1605 - 1615
DOI: 10.1051/jp1:1993203
J. Phys. I France 3 (1993) 1605-1615

Effects of electron irradiation on YBa 2CU 30 $\mathrm{_{7{-}\delta}}$ superconductor

A. Legris1, F. Rullier-Albenque1, E. Radeva1 and P. Lejay2

1  Laboratoire des Solides Irradiés (URA CNRS N$^{\circ}$ 1380), CEA-CEREM, Ecole Polytechnique, 91128 Palaiseau Cedex, France
2  CRTBT-CNRS, BP 166X, 38042 Grenoble Cedex, France

(Received 15 January 1993, revised 1 March 1993, accepted 15 March 1993)

We have irradiated YBa 2Cu 3O $_{7{-}\delta}$ single crystals with electrons of energy  E ranging from 0.1 to 2.4 MeV. From the measurements of the $T_{\rm c}$, reduction rate, $-\Delta \dot{T}_{\rm c}=-{\rm d}(\Delta T_{\rm c})/{\rm d}(\Phi t)$ with $\Phi t$ the irradiation fluence, we have clearly evidenced for the first time the influence of both copper and oxygen defects on the critical temperature. The analysis of the data, using calculated displacement cross-sections, allows us to extract the values of the displacement threshold energy for oxygen and copper atoms that we have evaluated as 10 and 15 eV respectively. We clearly show that irradiation effects have nothing to do with oxygen removal effects. However, the irradiation induced $T_{\rm c}$, decrease seems to be due to a pair breaking effect as suggested for Zn doped YBa 2Cu 3O $_{7{-}\delta}$ samples. On this subject, we bring experimental evidence which shows that the "classical" Abrikosov-Gorkov depairing mechanism by magnetic impurities is not appropriate to explain either the irradiation effects or the Zn substitution ones.

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