Spin Filter, Spin Amplifier and Other Spintronic Applications in Graphene Nanodisks

TL;DR

This paper explores the spin-filter effects in graphene nanodisks, demonstrating their potential for various spintronic applications by analyzing their response to different polarized currents using master equations and relaxation dynamics.

Contribution

It introduces the concept of spin filtering in graphene nanodisks and analyzes their dynamic response to polarized currents, proposing new spintronic device applications.

Findings

Finite-size effects influence spin filter behavior.

Quasi-ferromagnetic states exhibit long relaxation times.

Potential applications include spin memory and spin transistors.

Abstract

Graphene nanodisk is a graphene derivative with a closed edge. The trigonal zigzag nanodisk with size $N$ has $N$-fold degenerated zero-energy states. A nanodisk can be interpletted as a quantum dot with an internal degree of freedom. The grand state of nanodisk has been argued to be a quasi-ferromagnet, which is a ferromagnetic-like states with a finite but very long life time. We investigate the spin-filter effects in the system made of nanodisks and leads based on the master equation. The finite-size effect on spin filter is intriguing due to a reaction from the polarization of incoming current to a quasi-ferromagnet. Analyzing the relaxation process with the use of the Landau-Lifshitz-Gilbert equation, we explore the response to four types of incoming currents, namely, unpolarized current, perfectly polarized current, partially polarized current and pulse polarized current. We propose some applications for spintronics, such as spin memory, spin amplifier, spin valve, spin-field-effect transistor and spin diode.