Control of the nanosized defect network in superconducting thin films by target grain size

Moe Moe Aye,Hannes Rijckaert,Ermei Mäkilä,Mukarram Zaman Khan,Elmeri Rivasto,Petriina Paturi,Hannu Huhtinen,Christopher Haalisto,Esko Salojärvi,Heikki Palonen,Isabel Van Driessche

doi:10.1038/s41598-021-85304-4

Moe Moe Aye, Hannes Rijckaert + Show 9 more

Open Access

https://doi.org/10.1038/s41598-021-85304-4

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Journal: Scientific Reports	Publication Date: Mar 16, 2021
Citations: 9	License type: open-access

Affiliation: University of Turku, Ghent University

Abstract

A nanograined YBCO target, where a great number of grain boundaries, pores etc. exist, is shown to hold an alternative approach to future pulsed laser deposition based high-temperature superconductor thin film and coated conductor technologies. Although the nanograined material is introduced earlier, in this work, we comprehensively demonstrate the modified ablation process, together with unconventional nucleation and growth mechanisms that produces dramatically enhanced flux pinning properties. The results can be generalized to other complex magnetic oxides, where an increased number of defects are needed for modifying their magnetic and electrical properties, thus improving their usability in the future technological challenges.

Highlights

A nanograined YBCO target, where a great number of grain boundaries, pores etc. exist, is shown to hold an alternative approach to future pulsed laser deposition based high-temperature superconductor thin film and coated conductor technologies
The effect of target density and its crystal grain size on the critical current density Jc of the pulsed laser deposited YBCO thin films is systematically investigated in wide temperature, magnetic field and angular ranges
The absolute value of Jc and its anisotropy are obtained to be similar in the case with different target densities whereas the target grain size is observed to have a great impact on the flux pinning and vortex dynamics, producing a completely different shape of Jc(θ ) curve, especially around the YBCO a/b- and c-axes

Summary

Introduction

A nanograined YBCO target, where a great number of grain boundaries, pores etc. exist, is shown to hold an alternative approach to future pulsed laser deposition based high-temperature superconductor thin film and coated conductor technologies. Due to its simplicity and excellent performance on formation of the high density of natural defects, pulsed laser deposition (PLD) is one of the most versatile deposition techniques to get the most effective pinning of flux in high-temperature superconductor (HTS) YBa2Cu3O6+x (YBCO) films[1,2,3]. The most critical PLD parameters and their role in defect formation and flux pinning have been widely discussed e arlier[5,7,8,9,10,11,12,13,14,15], but the effect of target quality such as target density and especially its grain size is still not yet completely understood. The focus of attention in the main paper is in analyzing the relationship between the target grain size and the film structural characteristics, whereas the superconducting performance of the YBCO films is mainly discussed in the supporting information (SI)

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Results

Conclusion