Graphene-based Spin Caloritronics

TLDR

Thermally induced spin transport in magnetized zigzag graphene nanoribbons is investigated using first‑principles calculations. A temperature gradient across a magnetized zigzag graphene nanoribbon device drives opposite spin‑up and spin‑down currents. The spin Seebeck effect originates from asymmetric electron‑hole transmission spectra, spin currents can be fully polarized by back‑gate voltage, and thermal magnetoresistance can reach 10^4 %, indicating the feasibility of graphene‑based spin caloritronic devices.

Abstract

Thermally induced spin transport in magnetized zigzag graphene nanoribbons (M-ZGNRs) is explored using first-principles calculations. By applying temperature difference between the source and the drain of a M-ZGNR device, spin-up and spin-down currents flowing in opposite directions can be induced. This spin Seebeck effect in M-ZGNRs can be attributed to the asymmetric electron-hole transmission spectra of spin-up and spin-down electrons. Furthermore, these spin currents can be modulated and completely polarized by tuning the back gate voltage. Finally, thermal magnetoresistance of ZGNRs between ground states and magnetized states can reach 10(4)% without an external bias. Our results indicate the possibility of developing graphene-based spin caloritronic devices.