Structures and effects of radiation damage in cuprate superconductors irradiated with several-hundred-MeV heavy ions

TLDR

The study investigates how several‑hundred‑MeV heavy ions cause and systematically vary radiation damage in cuprate superconductors. Defect formation in cuprate superconductors depends on ion energy loss, crystal orientation, thermal conductivity/oxygen state, and preexisting defects, and is modeled by ion‑induced localized melting and anisotropic thermal conductivity. Au and Ag ion irradiation creates amorphous tracks while Cu and Si ions do not, and the resulting damage scales linearly with superconducting transition temperature and normal‑state resistivity.

Abstract

This paper reports a study of the nature and systematic variation of radiation damage to cuprate superconductors caused by several-hundred-MeV heavy ions. While irradiation of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ with 300-MeV ${\mathrm{Au}}^{24+}$ and 276-MeV ${\mathrm{Ag}}^{21+}$ ions produces columns of amorphous material along the ion trajectories, such defects are only created occasionally during irradiation with 236-MeV ${\mathrm{Cu}}^{18+}$ and not induced with 182-MeV ${\mathrm{Si}}^{13+}$. A comparative study of the defect formation in ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{\mathit{x}}$ and oxygen-reduced and ozone-treated ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$, shows that the degree of the radiation damage by the heavy ions depends on (a) the rate at which ions lose their energy in the target; (b) the crystallographic orientations with respect to the incident ion beam; (c) thermal conductivity and chemical state (oxygen concentration for ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$) of the sample; and (d) the extent of preexisting defects in the crystal. A theoretical model based on ion-induced localized melting and the effects of anisotropic thermal conductivity of these materials provides a basis for understanding the size and shape of the amorphous tracks. Measurements of the superconducting properties of ${\mathrm{Au}}^{24+}$- and ${\mathrm{Ag}}^{21+}$-irradiated ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ thin films show a universal linear scaling between the fractional areal damage versus the superconducting transition temperature and the normal-state resistivity.