Influence of defects on anisotropy of electrical resistivity in YBa2Cu3O7-δ

The influence of defects induced by irradiation with fast electrons on the anisotropy of the electrical resistance of YBa2Cu3O7-delta is investigated. The radiation exposure causes a decrease in the anisotropy of the electrical resistance in the normal state, thereby contributing to the isotropization of the quasiparticle spectrum due to the formation of a large number of defects in the form of Y, Ba, and Cu atoms displaced from their regular positions. The anisotropy is also expressed in the existence of various conductivity mechanisms along and across the layers. Thus, the anisotropy of the ideal phonon resistance, which exists both along and across the layers, increases with increasing temperature, tending to a constant value. In the region of the superconducting transition, a broadening of the transition due to the presence of microscopic inhomogeneities is observed in the plane of the layers, and several superconducting transitions are revealed across the layers due to the presence of macroscopic inhomogeneities in the sample.