Pulsed laser deposition of CeO₂ and Ce_1−xM_xO₂ (M = La, Zr): Application to insulating barrier in cuprate heterostructures*

Author： Berger S. Contour J.-P. Drouet M. Durand O. Khodan A. Michel D. Régi F.-X.

Publisher： Edp Sciences

E-ISSN： 1286-0050|1|3|295-299

ISSN： 1286-0042

Source： EPJ Applied Physics (The), Vol.1, Iss.3, 2010-03, pp. : 295-299

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Abstract

SrTiO₃ had been often tentatively used as an insulating barrier for HT superconductor/insulator heterostructures. Unfortunately, the deposition of SrTiO₃ on the YBa₂Cu₃O₇ inverse interface results in a poor epitaxial regrowth producing a high roughness dislocated titanate layer. Taking into account the good matching with YBa₂Cu₃O₇ and LaAlO₃, CeO₂ and Ce_1−xM_xO₂ (M = La, Zr), epitaxial layers were grown by pulsed laser deposition on LaAlO₃ substrates and introduced into YBa₂Cu₃O₇ based heterostructures as insulating barrier. After adjusting the growth parameters from RHEED oscillations, epitaxial growth is achieved, the oxide crystal axes being rotated by 45° from those of the substrate. The surface roughness of 250 nm thick films is very low with a rms value lower than 0.5 nm over 1 μm². The YBa₂Cu₃O₇ layers of a YBa₂Cu₃O₇/CeO₂/YBa₂Cu₃O₇ heterostructures grown using these optimized parameters show an independent resistive transition, when the thickness is larger than 25 nm, respectively at T_c₁ = 89.6K and T_c₂ = 91.4K.