Closed-loop electric currents and non-local resistance measurements with wide F/I/N tunnel contacts

TL;DR

This paper investigates how wide F/I/N tunnel contacts influence non-local voltage measurements in lateral spin valves, revealing persistent voltage modifications even with low-transparency contacts, which are crucial for accurate data interpretation.

Contribution

It demonstrates that voltage modifications due to closed-loop currents persist in F/I/N tunnel contacts, highlighting their importance in spin transport measurements.

Findings

Voltage modifications remain significant with F/I/N tunnel contacts.

Closed-loop currents influence non-local voltage measurements.

Data analysis must account for these effects in spin valve experiments.

Abstract

Lateral spin valves are used to generate and characterize pure spin currents. Non-local voltage measured in such structures provides information about spin polarization and spin decay rates. For wide high-transparency F/N contacts it was shown that the Johnson-Silsbee non-local effect is substantially enriched by closed-loop electric currents driven by local spin injection in the electrically dangling part of the valve. For valves with low-transparency F/I/N tunnel contacts such circular currents are strongly suppressed, yet we show that the voltage modifications persist, may be significant, and must be accounted for in the data analysis.