Spin dependent quantum interference in non-local graphene spin valves

TL;DR

This paper demonstrates quantum interference effects in non-local graphene spin valves, revealing strong modulation and polarity changes of spin signals, highlighting the potential for quantum coherent graphene in future spintronic devices.

Contribution

It uncovers quantum interference effects in graphene spin transport, showing the constriction acts as a spin filter and modulates the spin signal significantly.

Findings

Spin dependent contribution is two orders of magnitude larger than spin independent.

Non-local spin signal is strongly modulated and changes polarity with gate voltage.

The constriction acts as a spin filter device.

Abstract

Spin dependent electron transport measurements on graphene are of high importance to explore possible spintronic applications. Up to date all spin transport experiments on graphene were done in a semi-classical regime, disregarding quantum transport properties such as phase coherence and interference. Here we show that in a quantum coherent graphene nanostructure the non-local voltage is strongly modulated. Using non-local measurements, we separate the signal in spin dependent and spin independent contributions. We show that the spin dependent contribution is about two orders of magnitude larger than the spin independent one, when corrected for the finite polarization of the electrodes. The non-local spin signal is not only strongly modulated but also changes polarity as a function of the applied gate voltage. By locally tuning the carrier density in the constriction we show that the constriction plays a major role in this effect and indicates that it can act as a spin filter device. Our results show the potential of quantum coherent graphene nanostructures for the use in future spintronic devices.