Nonadiabatic pure spin pumping in zigzag graphene nanoribbons with proximity induced ferromagnetism

TL;DR

This paper demonstrates non-adiabatic quantum spin and charge pumping in ferromagnetic graphene nanoribbons using Floquet theory, revealing tunable pure spin, charge, and spin-polarized currents driven by phase-lagged ac gate voltages.

Contribution

It introduces a novel theoretical framework combining Floquet theory and Green's functions to analyze non-adiabatic spin and charge pumping in ferromagnetic graphene nanoribbons.

Findings

Pure spin pumping with zero net charge achieved.

Tunable pure charge and spin-polarized pumping demonstrated.

Dependence of spin polarization on energy level spacing and driving frequency.

Abstract

By combining Floquet theory with Green's function formalism, we present non-adiabatic quantum spin and charge pumping through a zigzag ferromagnetic graphene nanoribbon including a double-barriers structure driven weakly by two local $ac$ gate voltages operating with a phase-lag. Over a wide range of Fermi energies, interesting quantum pumping such as i) pure spin pumping with zero net charge pumping, ii) pure charge pumping and iii) fully spin polarized pumping can be achieved by tuning and manipulating driving frequency in the non-adiabatic regime. Spin polarized pumping which is measurable using the current technology depends on the competition between the energy level spacing and driving frequency.