Magnetic adatoms in two and four terminal graphene nanoribbons: A comparison between their spin polarized transport

Abstract

We study the charge and spin transport in two and four terminal graphene nanoribbons (GNR) decorated with random distribution of magnetic adatoms. The inclusion of the magnetic adatoms generates only the z-component of the spin polarized conductance via an exchange bias in the absence of Rashba spin-orbit interaction (SOI), while in presence of Rashba SOI, one is able to create all the three (x, y and z) components. This has important consequences for possible spintronic applications. The charge conductance shows interesting behaviour near the zero of the Fermi energy. Where in presence of magnetic adatoms the familiar plateau at 2e 2 /h vanishes, thereby transforming a quantum spin Hall insulating phase to an ordinary insulator. The local charge current and the local spin current provide an intuitive idea on the conductance features of the system. We found that, the local charge current is independent of Rashba SOI, while the three components of the local spin currents are sensitive to Rashba SOI. Moreover the fluctuations of the spin polarized conductance are found to be useful quantities as they show specific trends, that is, they enhance with increasing adatom densities. A two terminal GNR device seems to be better suited for possible spintronic applications.

Half‐Metallic Devices from Armchair Graphene Nanoribbons with Transition Metal Guest Atoms

“…Further, we will pursue the question of the magnetic effects exerted by aGNR adatoms on currents traversing them. Previous studies have dealt with problems of TM atom adsorption on a graphene substrate in terms of geometric, electronic, and magnetic features, [42,43] or with current polarization induced by TM adatoms on graphene sheets [44,45] . These studies will be extended to molecular and cluster adsorbates as potential devices to control current spin polarization.…”

“…Previous studies have dealt with problems of TM atom adsorption on a graphene substrate in terms of geometric, electronic, and magnetic features, [42,43] or with current polarization induced by TM adatoms on graphene sheets. [44,45] These studies will be extended to molecular and cluster adsorbates as potential devices to control current spin polarization. Comparison will be made with TM atom substitution, as considered in this work.…”