Generation of fully spin-polarized currents in three-terminal graphene-based transistors

TL;DR

This paper introduces a novel three-terminal graphene device that generates fully spin-polarized currents without magnetic fields, using Hubbard interactions and geometric modulation to control spin polarization.

Contribution

It presents a new graphene-based spin transistor design leveraging Hubbard repulsion and device geometry for spin current control without external magnetic fields.

Findings

Hubbard repulsion enables spin polarization without magnetic fields.

Modulating drain voltages controls spin polarization.

Device geometry significantly affects spin current efficiency.

Abstract

We propose three-terminal spin devices with graphene nanoribbons (terminals) and a graphene flake (channel) to generate a highly spin-polarized current without an external magnetic field or ferromagnetic electrodes. The Hubbard repulsion within the mean-field approximation plays the main role to separate the unpolarized electric current at the source terminal into spin-polarized currents at the drain terminals. It is shown that by modulating one of the drain voltages, a fully spin-polarized current can be generated in the other drain terminal. In addition, the geometry of the channel and the arrangement of edge atoms have significant impact on the efficiency of spin currents in the three-terminal junctions which might be utilized in generation of graphene-based spin transistors.