Tolerance to deformation and flux pinning in superconducting amorphous molybdenum nitride thin films grown on flexible polyimide

Penetration depth and critical fields in superconducting NbTi thin films grown by co-sputtering at room temperature

“…To study the feasibility of using flexible substrates in the fabrication of superconducting films, we have studied the representative properties of superconducting a 150 nm thick NbTi film grown over flexible Kapton. The aim is to analyze their properties, considering the tolerance to mechanical deformation reported for wires [20] and their potential application in cryogenic devices [9]. Additionally, as deduced from the literature and the presented results, the critical temperature is slightly higher than that of metallic Nb, and there is also a large upper critical field [37].…”

“…The film displays a residual resistivity ratio (RRR) of 1.3 and a room-temperature resistivity (ρ RT ) of 5 μΩ•cm. Figure 3(a) displays a summary of the normalized resistance as a function of temperature without and with applied fields up to 9 T. The sample is characterized by a sharp superconducting transition with T c = 9.65 K (defined at 50% of the change in resistance), as expected for high-quality alloys [20,26]. Indeed, for zero field, considering the onset of T c (defined as 90% of the change in resistance) and the offset of T c (defined as 10% of the change in resistance), the difference is smaller than 0.1 K. As a magnetic field is applied, the transition shifts to lower temperatures while conserving its sharpness.…”

“…Thin films, produced through techniques such as sputtering, enable deposition at room temperature or low temperatures, minimizing Ti precipitation and preserving outstanding properties, such as large H c2 values. This also opens up the possibility of designing thin films on flexible/polymeric substrates, where deposition temperatures above room temperature could potentially chemically degrade them [9,10,20]. Given the potential application of NbTi alloying thin films, it is relevant to evaluate their superconducting parameters to assess their suitability for use in cryogenic technologies.…”