Graphene Spintronics

The isolation of graphene has triggered an avalanche of studies into the spin-dependent physical properties of this material, as well as graphene-based spintronic devices. Here we review the experimental and theoretical state-of-art concerning spin injection and transport, defect-induced magnetic moments, spin-orbit coupling and spin relaxation in graphene. Future research in graphene spintronics will need to address the development of applications such as spin transistors and spin logic devices, as well as exotic physical properties including topological states and proximity-induced phenomena in graphene and other 2D materials.Comment: 47 Pages, 6 figure

Contact Induced Spin Relaxation in Graphene Spin Valves with Al2O3 and MgO Tunnel Barriers

We investigate spin relaxation in graphene by systematically comparing the roles of spin absorption, other contact-induced effects (e.g. fringe fields, etc.), and bulk spin relaxation for graphene spin valves with MgO barriers, Al2O3 barriers, and transparent contacts. We obtain effective spin lifetimes by fitting the Hanle spin precession data with two models that include or exclude the effect of spin absorption. Results indicate that additional contact-induced spin relaxation other than spin absorption dominates the contact effect. For tunneling contacts, we find reasonable agreement between the two models with median discrepancy of ~20% for MgO and ~10% for Al2O3.Comment: 21 pages, 4 figure

Magnetic Moment Formation in Graphene Detected by Scattering of Pure Spin Currents

Hydrogen adatoms are shown to generate magnetic moments inside single layer graphene. Spin transport measurements on graphene spin valves exhibit a dip in the non-local spin signal as a function of applied magnetic field, which is due to scattering (relaxation) of pure spin currents by exchange coupling to the magnetic moments. Furthermore, Hanle spin precession measurements indicate the presence of an exchange field generated by the magnetic moments. The entire experiment including spin transport is performed in an ultrahigh vacuum chamber, and the characteristic signatures of magnetic moment formation appear only after hydrogen adatoms are introduced. Lattice vacancies also demonstrate similar behavior indicating that the magnetic moment formation originates from pz-orbital defects.Comment: accepted to Phys. Rev. Let