Incoherent charge transport induced by irradiation of YBCO single crystals with MeV electrons

Abstract

Irradiation with electrons is an efficient approach to induce a large number of defects with minimal impact on the material composition. In high-temperature superconducting cuprates, electrons with MeV energies produce point defects in the form of interstitial ions and vacancies that act as efficient scattering centers. Here, we analyze the changes in the electronic transport along the c-axis of $$\hbox {YBa}_2\hbox {Cu}_3\hbox {O}_{7-\delta }$$ single crystals after their irradiation with $$0.5-2.5$$ MeV electrons at $$T \lesssim 10$$ K and a dose of $$10^{18}$$ cm $$^{-2}$$ . While a variable-range hopping conductivity associated with some mesoscopic length scale is observed in the non-irradiated samples, we reveal a two-step superconducting transition in the irradiated samples, that attests to the presence of an additional, macroscopic inhomogeneity induced by the electron irradiation.