Spin Seebeck Effect in Graphene

TL;DR

This paper presents a microscopic theory of the spin Seebeck effect in graphene, revealing quantum oscillations and temperature-dependent peak shifts in spin currents at a ferromagnetic insulator-graphene interface.

Contribution

It introduces a detailed microscopic model for SSE in graphene and compares it with spin pumping, highlighting quantum oscillations and temperature effects.

Findings

Thermally driven SSE shows quantum oscillations similar to spin pumping.

Peak shifts in oscillations occur due to thermally excited magnons at higher temperatures.

The theory predicts temperature-dependent quantum oscillation patterns.

Abstract

We develop a microscopic theory of the spin Seebeck effect (SSE) at the interface of a bilayer system of a ferromagnetic insulator and graphene. We compare the tunneling spin current at the interface because of the SSE and the spin pumping (SP), where the SSE and SP are induced by the temperature gradient and the microwave irradiation, respectively. We demonstrate that the thermally driven SSE exhibits a quantum oscillation pattern similar to that predicted in coherently driven SP. Additionally, we show a peak shift of the quantum oscillation owing to the contribution of thermally excited magnons with higher frequencies, which becomes particularly pronounced at higher temperatures.