Negative nonlocal and local voltages (resistances) in a quasi-one-dimensional superconducting aluminum structure

TL;DR

This study investigates nonlocal electron transport in a quasi-one-dimensional aluminum superconducting structure, revealing negative voltages caused by quasiparticle currents near the critical temperature.

Contribution

It provides experimental and theoretical analysis of negative voltages in a normal-superconducting aluminum structure considering superconducting fluctuations.

Findings

Negative nonlocal and local voltages observed near critical temperature.

Voltage peaks depend on temperature and magnetic field.

Theoretical models include equilibrium and nonequilibrium fluctuations.

Abstract

To study a nonlocal electron transport in an aluminum superconducting quasi-one-dimensional structure, we measured negative nonlocal (local) direct current voltages in the structure in a magnetic field near the critical temperature. The structure is a normal-superconducting at $T_{cn}<T<T_{cw}$ ($T_{cn}$ and $T_{cw}$ are the critical temperatures for narrow and wide wires, respectively, making up this structure). Negative voltage arises due to a quasiparticle current flowing through the N-S interface. We plotted the experimental and theoretical temperature and magnetic-field dependences of current, resistance and voltage corresponding to the peak of negative voltage, taking into account either equilibrium or nonequilibrium superconducting fluctuations.