Fluctuations-Driven Superconductivity in Nitrogen-Doped Disordered Tungsten Rhenium Films

Abstract

We report a systematic study of nitrogen-doped superconducting tungsten-rhenium (WReN) thin films with thicknesses ranging from 5 to 60 nm, focusing on the interplay of disorder, superconducting fluctuations (SF), quantum fluctuations (QF), and weak localization (WL). The introduction of nitrogen allows fine-tuning of disorder, making WReN an ideal platform to explore quantum transport phenomena compared to related compounds such as WRe. To characterize both superconducting and normal-state properties, we employ Hall effect, magnetoresistance, and magnetoconductivity (MC) measurements for WReN films. Hall measurements provide complementary insight into carrier density, mobility, and disorder in the normal state, while SF, WL, and QF analyses reveal fundamental superconducting parameters, including critical temperature, upper critical field, coherence length and superconducting-insulating transition. Further, MC analyses were used for extracting relaxation times, which were found to be of the order of picoseconds. These results highlight the key role of disorder in shaping both the quantum transport and superconducting behavior of WReN films, offering a foundation for future studies in quantum materials and superconducting device applications.