Oxygen diffusion in off–c-axis normal-state

$\textmd{Bi}_2\textmd{Sr}_2\textmd{CaCu}_2\textmd{O}_{8+\delta}$

films

Author： Gramm A. Zahner Th. Spreitzer U. Rössler R. Pedarnig J. D. Bäuerle D. Lengfellner H.

Publisher： Edp Sciences

E-ISSN： 1286-4854|49|4|501-506

ISSN： 0295-5075

Source： EPL (EUROPHYSICS LETTERS), Vol.49, Iss.4, 2010-03, pp. : 501-506

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Abstract

The anisotropy of the oxygen diffusion in the high-T_c-super con duc tor Bi₂Sr₂CaCu₂O$_{8+\delta}$ was investigated using off–c-axis prepared thin films. High-quality oriented films with thickness 1000 Å and c-axis inclined by a tilt angle α with respect to the normal of the film surface were grown up to $\alpha = 15^\circ$. Oxygen diffusion following a small change of the ambient oxygen partial pressure in the temperature range $200\mbox{--}400\un{^\circ C}$ was monitored by in situ resistance measurements. Diffusion times according to an activated process $\tau^{-1}=\tau_0^{-1}\exp[-E/k_{\rm B}T]$ were found, with E = 0.6 eV and $\tau_0 = \tau_0(\alpha)$ becoming smaller with increasing tilt angle. A comparison of the experimental $\tau_0(\alpha)$ with a calculation of $\tau_0$ for an ideal monocrystalline film suggests that as-grown films consist of crystalline grains with la te ral dimensions $\sim 1\un{\mu m}$.