Cooperative phenomenon in a rippled graphene: Chiral spin guide

TL;DR

This paper investigates how curved ripples in graphene can act as spin filters, enabling selective transmission of electron spins through curvature-induced spin-orbit coupling, with effects amplified in multiple ripple structures.

Contribution

It introduces an analytical model for spin transport in rippled graphene, revealing how connected ripples enhance spin filtering effects via curvature-induced spin-orbit coupling.

Findings

Curvature induces spin-orbit coupling creating transparent windows for specific spins.

Multiple connected ripples significantly enhance spin filtering.

Analytical expressions for spin transmission probabilities are provided.

Abstract

We analyze spin scattering in ballistic transport of electrons through a ripple at a normal incidence of an electron flow. The model of a ripple consists of a curved graphene surface in the form of an arc of a circle connected from the left-hand and right-hand sides to two flat graphene sheets. At certain conditions the curvature induced spin-orbit coupling creates a transparent window for incoming electrons with one spin polarization simultaneously with a backscattering of those with opposite polarization. This window is equally likely transparent for electrons with spin up and spin down that move in opposite directions. The spin filtering effect being small in one ripple becomes prominent with the increase of N consequently connected ripples that create a graphene sheet of the sinusoidal type. We present the analytical expressions for spin up (down) transmission probabilities as a function of N connected ripples.