Electronic spin drift in graphene field effect transistors

TL;DR

This study investigates how applying a DC electric field influences electron spin transport in graphene transistors, revealing significant modulation of spin signals and their dependence on carrier type and conduction regime at room temperature.

Contribution

It provides the first quantitative analysis of spin drift effects in graphene transistors, demonstrating control over spin signals via electric fields and carrier type.

Findings

Spin signals vary by up to ±50% with applied electric fields.

Reversal of drift effect when switching from holes to electrons.

Strong suppression of drift effect near the Dirac point.

Abstract

We studied the drift of electron spins under an applied DC electric field in single layer graphene spin valves in a field effect transport geometry at room temperature. In the metallic conduction regime ($n \simeq 3.5 \times 10^{16}$ m$^{-2}$), for DC fields of about $\pm$70 kV/m applied between the spin injector and spin detector, the spin valve signals are increased/decreased, depending on the direction of the DC field and the carrier type, by as much as $\pm$50%. Sign reversal of the drift effect is observed when switching from hole to electron conduction. In the vicinity of the Dirac neutrality point the drift effect is strongly suppressed. The experiments are in quantitative agreement with a drift-diffusion model of spin transport.