Phase purity and surface morphology of high-<i>J</i>_c superconducting Bi₂Sr₂Ca₁Cu₂O_8+δ thin films

Author(s)

Sandra Keppert, Bernd Aichner, Rajdeep Adhikari, Bogdan Faina, Wolfgang Lang, Johannes D. Pedarnig

Abstract

Bi₂Sr₂Ca₁Cu₂O_8+δ (Bi-2212) thin films with thicknesses less than 50 nm (<20 unit cells) are grown by pulsed laser deposition (PLD) onto (001) LaAlO₃ (LAO) single crystal substrates. Phase-pure and smooth c-axis oriented Bi-2212 films with optimal oxygen doping, critical temperature T_c0 up to 86 K, and critical current density J_c(60 K) above 1 MA/cm² are obtained for samples that are annealed in situ at temperatures below 700 °C. At higher temperature Bi-2212 films on LAO substrates partially decompose to non-superconducting impurity
phases, while films on MgO and SrTiO₃ substrates are stable. The broadening ΔT_c of the metal-to-superconductor resistive phase transition in magnetic fields is much larger for thin films of Bi-2212 as compared to YBa₂Cu₃O₇. The magnetic field-induced suppression of T_c0 is stronger for Bi-2212 films containing impurity phases as compared to the phase-pure Bi-2212 films. The degradation of LAO substrate crystals after several steps of deposition and chemical removal of the Bi-2212 layer is investigated. New, commercially prepared substrates
provide Bi-2212 films with smallest surface roughness (3 nm) and strong out-of-plane texture. However, thin films of almost the same quality are obtained on re-used LAO substrates that are mechanically polished after the chemical etching.

Organisation(s)

Electronic Properties of Materials

External organisation(s)

Johannes Kepler Universität Linz

Journal

Applied Surface Science

Volume

636

No. of pages

10

ISSN

0169-4332

DOI

https://doi.org/10.1016/j.apsusc.2023.157822

Publication date

06-2023

Peer reviewed

Yes

Austrian Fields of Science 2012

103033 Superconductivity, 103018 Materials physics

Keywords

ASJC Scopus subject areas

Condensed Matter Physics, Surfaces, Coatings and Films, Surfaces and Interfaces

Portal url

https://ucris.univie.ac.at/portal/en/publications/phase-purity-and-surface-morphology-of-highjc-superconducting-bi2sr2ca1cu2o8-thin-films(01ede269-11c1-41da-9deb-9e1f7b2538fe).html