Freestanding GdBa2Cu3O7 Thin Films via Optimized Buffer Layer Design: Preserving Superconducting Properties

TL;DR

This paper presents a method to produce freestanding GdBCO superconducting films using optimized buffer layers and a water-soluble sacrificial layer, preserving their superconducting properties after lift-off.

Contribution

It systematically investigates buffer-layer configurations, identifying a LaAlO3/SrTiO3 bilayer as essential for maintaining high Tc and structural integrity.

Findings

LaAlO3/SrTiO3 bilayer buffer maintains Tc at ~92 K after lift-off.

Reversed SrTiO3/LaAlO3 buffer suppresses Tc.

Buffer-layer design critically affects film quality and superconducting properties.

Abstract

Freestanding GdBa2Cu3O7 (GdBCO) superconducting thin films were fabricated using a water-soluble Sr3Al2O6 (SAO) sacrificial layer in combination with thermal release tape. An amorphous Al2O3 capping layer was introduced to suppress crack formation during the lift-off process. The influence of buffer-layer design inserted between the GdBCO and SAO layers was systematically investigated with respect to structural integrity and superconducting properties after lift-off. A LaAlO3/SrTiO3 bilayer buffer was found to be essential for maintaining epitaxial growth and a superconducting transition temperature (Tc) of approximately 92 K after lift-off, comparable to that of the as-grown films. In contrast, a reversed SrTiO3/LaAlO3 bilayer and single-layer buffer structures led to a suppression of Tc, highlighting the critical role of stacking sequence. These results demonstrate that optimization of the buffer-layer design is a key factor for realizing high-quality freestanding GdBCO films while maintaining their superconducting characteristics.