Strain-modulation and enhancement of superconductivity in flexible YBa₂Cu₃O₇ thin films

Abstract

The development of large, high-quality flexible high-temperature superconducting films is a crucial focus in flexible electronics research, posing challenges and offering promising applications. Among candidate materials, YBCO is a high-performance high-temperature superconductor. However, the mechanical behavior and stress evolution of its flexible thin films remain a critical gap in current research, hindering further development. In this investigation, a YBa₂Cu₃O₇/SrTiO₃/Sr₄Al₂O₇ heterostructure was synthesized on SrTiO₃ substrates via pulsed laser deposition (PLD). By selectively etching the water-soluble Sr₄Al₂O₇ sacrificial layer, crack-free, high-quality freestanding YBa₂Cu₃O₇ films at the millimeter scale were successfully fabricated, and remarkable improvements in superconducting properties were achieved, with critical transition temperature and magnetic shielding response approaching the intrinsic characteristics of bulk YBa₂Cu₃O₇. Bending experiments demonstrate that the superconductivity of freestanding YBCO films can be effectively modulated by mechanical strain. Under in‑plane compressive strain, the film exhibits an increased superconducting transition temperature, whereas in‑plane tensile strain diminishes superconductivity. This study not only presents a dependable approach for producing high-quality flexible high-temperature superconducting films but also establishes a fundamental strain-modulation mechanism. By controlling bending, achieved enhancement and continuous modulation of the superconducting properties. These results are essential for the advancement of new-generation flexible electronic devices based on high-temperature superconducting materials.

Keywords

YBa₂Cu₃O₇ thin films / flexible superconducting material / stress evolution / strain regulation / enhanced superconductivity

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