Reflection high-energy electron diffraction oscillations modulated by laser-pulse deposited YBa2Cu3O7-x.

Abstract

Reflection high-energy electron diffraction oscillations during pulsed laser ablation of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathit{x}}$ on ${\mathrm{SrTiO}}_{3}$(100) substrates were measured. We have found for the first time that the oscillations are modulated by the laser-pulse repetition frequency. Each laser pulse deposits 0.14 nm of material. This causes the specularly reflected intensity to decrease instantaneously, but then it increases exponentially due to crystallization. An activation energy of 0.7\ifmmode\pm\else\textpm\fi{}0.1 eV and a diffusion constant of 1.4\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}12}$ ${\mathrm{cm}}^{2}$/sec at 720\ifmmode^\circ\else\textdegree\fi{}C for the formation of c-axis oriented films was determined.