Spin filter and spin valve in ferromagnetic graphene

TL;DR

This paper demonstrates that a EuO-induced, top-gated ferromagnetic graphene junction can function as both a spin filter and a spin valve, with controllability via gate voltage and robustness at finite temperatures.

Contribution

It introduces a novel ferromagnetic graphene device that acts as a tunable spin filter and spin valve, leveraging EuO-induced ferromagnetism and gate control.

Findings

Effective spin filtering and spin valve operation controlled by back gate voltage.

Device maintains functionality with practical metal contacts and at finite temperature.

Spin filter operates at higher temperature than the spin valve.

Abstract

We propose and demonstrate that a EuO-induced and top-gated graphene ferromagnetic junction can be simultaneously operated as a spin filter as well as a spin valve. We attribute such a remarkable result to a coexistence of a half-metal band and a common energy gap for opposite spins in ferromagnetic graphene. We show that, both the spin filter and the spin valve can be effectively controlled by a back gate voltage, and they survive for practical metal contacts and finite temperature. Specifically, larger single spin currents and on-state currents can be reached with contacts with work functions similar to graphene, and the spin filter can operate at higher temperature than the spin valve.