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Clean superconductivity in electron doped Pr2−x Cex CuO4+δ thin films hetero-epitaxially grown on SrTiO3 by reactive molecular beam epitaxy

Published online by Cambridge University Press:  03 November 2016

Ai Ikeda ,
Hiroshi Irie ,
Hideki Yamamoto  and
Yoshiharu Krockenberger
Ai Ikeda*
Affiliation:
NTT Basic Research Laboratories, NTT Corporation, Atsugi, Kanagawa 243-0198, Japan
Hiroshi Irie
Affiliation:
NTT Basic Research Laboratories, NTT Corporation, Atsugi, Kanagawa 243-0198, Japan
Hideki Yamamoto
Affiliation:
NTT Basic Research Laboratories, NTT Corporation, Atsugi, Kanagawa 243-0198, Japan
Yoshiharu Krockenberger
Affiliation:
NTT Basic Research Laboratories, NTT Corporation, Atsugi, Kanagawa 243-0198, Japan
*
a) Address all correspondence to this author. e-mail: ikeda.ai@lab.ntt.co.jp
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Abstract

Pr2−x Cex CuO4+δ thin films were grown hetero-epitaxially on (001) SrTiO3 substrates using ozone-assisted molecular beam epitaxy. High-quality epilayers with a cerium concentrations of x = 0.15 were grown and characterized electrically, structurally, and by magnetization measurements. The Pr2−x Cex CuO4+δ films were found to maintain the tetragonal Nd2CuO4 (T′) crystal structure with a linear dependence of lattice constant on the Ce concentration. The superconductivity of the Pr2−x Cex CuO4+δ films was maintained up to x ≈ 0.23 with a T c up to 12.6 K. For x < 0.15, control of the oxygen concentration δ by annealing is crucial for the induction of superconductivity in Pr2−x Cex CuO4+δ and this still holds for x > 0.20. We show that the electron mean free path length $\ell$ may be significantly enhanced by optimizing those annealing conditions. Moreover, the enhancement of $\ell$ leads to a reduction of the upper critical field, suggesting that superconductivity of Pr2−x Cex CuO4+δ is to be considered in the clean limit.

Keywords

superconductingmolecular beam epitaxyscanning transmission electron microscopy
Type
Invited Papers
Information
Journal of Materials Research , Volume 31 , Issue 22 , 28 November 2016 , pp. 3522 - 3529
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Copyright © Materials Research Society 2016 

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