Fluctuation effects in superconducting nanowires under electric field

Abstract

This study applies the time-dependent Ginzburg–Landau (TDGL) theory with thermal noise to analyze the thermoelectric and transport properties of superconducting Sn nanowires, focusing on the thermopower (${\alpha }_{xx}$) and the phase transition characteristics in the S-shaped $J$-$E$ curves. We observe significant contributions from superconducting Cooper pairs, which remain nonzero above the critical temperature ($T_c$), indicating residual superconductivity due to strong thermal fluctuations. The S-like shape in the $J$-$E$ curves is attributed to a dynamical instability transition temperature ($T^{\ast }$) at approximately 2.9 K, where thermal fluctuations dominate. Furthermore, we compare the resistance in the linear response to experimental data for Sn nanowires both below and above $T_c$. Below $T_c$, the resistance sharply decreases, reflecting the robust superconducting state, while above $T_c$, it increases, aligning with normal state behavior. In nonlinear response case, our results indicate that high electric fields can be effectively used to suppress order-parameter fluctuations and the electrical conductivity in superconducting nanowires. The findings provide critical insights into the thermoelectric behavior and phase transitions in Sn nanowires, highlighting the importance of Cooper pair dynamics in shaping the transport properties of one-dimensional superconductors. This understanding is essential for the development of advanced nanoelectronic devices leveraging these unique superconducting properties.