Superconducting properties of MgB2 thin films prepared on flexible plastic substrates

TL;DR

This study demonstrates the successful fabrication of flexible MgB2 superconducting thin films on plastic substrates, exhibiting promising superconducting properties and mechanical flexibility suitable for various applications.

Contribution

It introduces a novel vacuum co-deposition and rapid annealing method for producing flexible MgB2 superconducting films on plastic substrates.

Findings

Superconducting transition at ~33 K

Critical current density > 7x10^5 A/cm^2 at 4.2 K

Films maintain properties after bending and cutting

Abstract

Superconducting MgB2 thin films were prepared on 50-micrometer-thick, flexible polyamide Kapton-E foils by vacuum co-deposition of Mg and B precursors with nominal thickness of about 100 nm and a special ex-situ rapid annealing process in an Ar or vacuum atmosphere. In the optimal annealing process, the Mg-B films were heated to approximately 600 C, but at the same time, the backside of the structures was attached to a water-cooled radiator to avoid overheating of the plastic substrate. The resulting MgB2 films were amorphous with the onset of the superconducting transition at T_(c,on) about 33 K and the transition width of approximately 3 K. The critical current density was > 7x10^5 A/cm^2 at 4.2 K, and its temperature dependence indicated a granular film composition with a network of intergranular weak links. The films could be deposited on large-area foils (up to 400 cm^2) and, after processing, cut into any shapes (e.g., stripes) with scissors or bent multiple times, without any observed degradation of their superconducting properties.