Impact of Oxygen Diffusion on Superconductivity in YBa${}_2$Cu${}_3$O${}_{7-\delta }$ Thin Films Studied by Positron Annihilation Spectroscopy

Abstract

The oxygen deficiency $\delta$ in YBa${}_2$Cu${}_3$O${}_{7-\delta }$ (YBCO) plays a crucial role for affecting high-temperature superconductivity. We applied (coincident) Doppler broadening spectroscopy of the electron-positron annihilation line to study in situ the temperature dependence of the oxygen concentration and its depth profile in single crystalline YBCO film grown on SrTiO${}_3$ (STO) substrates. The oxygen diffusion during tempering was found to lead to a distinct depth dependence of $\delta$, which is not accessible using X-ray diffraction. A steady-state reached within a few minutes is defined by both, the oxygen exchange at the surface and at the interface to the STO substrate. Moreover, we revealed the depth dependent critical temperature $T_{\mathrm{c}}$ in the as prepared and tempered YBCO film.

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Cited by in corpus (1)

• Novel Data Analysis Tool for the Evaluation of Coincidence Doppler Broadening Spectra of the Positron-Electron Annihilation Line