Influence of thickness on the microstructure and performance of high-quality REBCO superconducting films fabricated via pulsed laser deposition technique with and without APCs

Violetta Poletto Dotsenko,¹, A. Angrisani Armenio², A. Mancini², A. Rufoloni², J. Hänisch³, Y. Rahman³, B. Holzapfel³, N. Pompeo¹, G. Sotgiu¹ and F. Rizzo²

¹Roma Tre University, Department of Industrial, Electronic and Mechanical Engineering, via Vito Volterra 62, 00154 Rome, Italy

²ENEA, Frascati Research Centre, FSN Department, Superconductivity Section, 00044 Frascati, Italy

³Institute for Technical Physics, Karlsruhe Institute for Technology, 76131 Karlsruhe, Germany

Biography of presenting author: Ms. Violetta Poletto Dotsenko studied Industrial Chemistry at the University “Sapienza”, Rome, Italy and completed her Master’s degree in 2021 and subsequently joined Roma Tre University, where she is currently conducting her research activities on superconducting materials REBCO at Research Center ENEA Frascati. She is pursuing her PhD in Applied Electronics under the supervision of Dr. Francesco Rizzo, with Prof. Giovanni Sotgiu serving as her Roma Tre University supervisor. She is currently carrying out an international internship at the Karlsruhe Institute of Technology (KIT), focused on the study and characterization of YBCO coated conductors at an industrial level.

Abstract

Superconductivity, discovered in the early 1900s, is defined by zero electrical resistance and the complete expulsion of magnetic fields, properties that make superconductors highly attractive for advanced applications, nowadays. Second-generation high-temperature superconductors (2G-HTS), notably REBa₂Cu₃O_7-γ (REBCO; RE, rare-earth element) materials, have emerged as key functional materials for sustainable energy and next-generation technologies. Their ability to operate well above liquid helium temperatures enables more energy-efficient systems for power transmission, medical imaging, and advanced scientific instrumentation [1] [2].

YBCO, one of the most promising materials for advanced superconducting technologies, exhibits excellent properties as an epitaxial film, providing significant advantages over low-temperature superconductors (LTS) under high-field conditions [3]. Undoubtedly, Pulsed Laser Deposition (PLD) is a versatile and precise technique for fabricating YBCO films, offering precise control over composition, crystalline quality, and interfacial microstructure — key factors for achieving high critical current density (J_c) and transition temperature (T_c). By tuning the main deposition parameters, such as laser energy density, repetition rate, and deposition time, films with varying thicknesses and structural and morphological characteristics can be obtained. However, only a narrow window of PLD parameters ensures optimal stoichiometry and high crystalline quality in YBCO films. To address this, we performed a systematic study of deposition conditions and evaluated their influence on phase formation and stoichiometric control, with the aim of promoting a high-quality epitaxial c-axis growth in thick YBCO films.

The thickness effect in REBCO thick superconducting layers has been one of the main challenges in the last decade for achieving high-efficiency performance suitable for large-scale production. Consequently, this study was mainly focused on increasing in film thickness of YBCO, while aiming to maintain high current density values, and on introducing different Artificial Pinning Centers (APCs) such as Ba₂Y(Nb/Ta)O₆ (BYNTO) and BaHfO₃ (BHO) to enhance the superconducting performance of the material.

In terms of superconductivity, YBCO pristine thin film exhibits exceptional high critical current densities, exceeding 3 MA/cm² at 4.2 K under magnetic fields up to 18 T and reaching approximately 34 MA/cm² at 4.2 K in self-field conditions. These high J_c values are attributed to a natural pinning mechanism arising from the thin film's nanostructured morphology. A correlation between microstructure, thickness and enhanced superconducting properties has been established. In addition, both the magnetic properties of the material under high magnetic fields and its structural characteristics are thoroughly investigated for doped and undoped films, in order to correlate the microstructure with the superconducting performance.

References:

[1] C. Yao e Y. Ma, «Superconducting materials: Challenges and opportunities for large-scale applications», iScience, vol. 24, fasc. 6, p. 102541, giu. 2021, doi: 10.1016/j.isci.2021.102541.

[2] Y. Zhao, Y. Wu, A. Goyal, H. Huhtinen, P. Paturi, e Y. Tsuchiya, «Commercial compact fusion triggered REBCO tape industry: Pulsed laser deposition technology opportunities and challenges», Superconductivity, vol. 15, p. 100188, set. 2025, doi: 10.1016/j.supcon.2025.100188.

[3] J. L. MacManus-Driscoll e S. C. Wimbush, «Processing and application of high-temperature superconducting coated conductors», Nat Rev Mater, vol. 6, fasc. 7, pp. 587–604, mar. 2021, doi: 10.1038/s41578-021-00290-3.