Non-linear spin Seebeck effect due to spin-charge interaction in graphene

TL;DR

This paper demonstrates a novel non-linear spin-charge interaction in graphene, where spin currents induce charge potentials through energy-dependent conductivity, advancing spintronics understanding.

Contribution

It introduces a new non-linear spin-charge interaction mechanism in graphene, expanding the understanding of spin-charge coupling beyond traditional methods.

Findings

Detection of non-local spin signals with non-magnetic detectors

Observation of spin-induced charge potentials in graphene

Validation of energy-dependent conductivity's role in spin-charge interaction

Abstract

The abilities to inject and detect spin carriers are fundamental for research on transport and manipulation of spin information. Pure electronic spin currents have been recently studied in nanoscale electronic devices using a non-local lateral geometry, both in metallic systems and in semiconductors. To unlock the full potential of spintronics we must understand the interactions of spin with other degrees of freedom, going beyond the prototypical electrical spin injection and detection using magnetic contacts. Such interactions have been explored recently, for example, by using spin Hall or spin thermoelectric effects. Here we present the detection of non-local spin signals using non-magnetic detectors, via an as yet unexplored non-linear interaction between spin and charge. In analogy to the Seebeck effect, where a heat current generates a charge potential, we demonstrate that a spin current in a paramagnet leads to a charge potential, if the conductivity is energy dependent. We use graphene as a model system to study this effect, as recently proposed. The physical concept demonstrated here is generally valid, opening new possibilities for spintronics.