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Department Spin and Topology in Quantum Materials

Graphene for spintronics

This activity began with the observation of quasifreestanding graphene on nickel(111) after intercalation of gold which also caused a measurable spin-orbit splitting in the graphene π-band of ~13 meV (Varykhalov 2008). Meanwhile, sample growth has been improved considerably so that giant spin-orbit splittings (Rashba splittings) of ~100 meV are obtained. The figures to the left show the intact Dirac cone of the π-band signalling quasifreestanding graphene. The figures to the right show the spin-resolved spectra (spin channels in blue and red), taken at the cross marks in the Dirac cone. The reason for the giant spin-orbit effect is found in a surprisingly strong hybridization of the graphene π-band with d-states of the gold (Marchenko 2012).

A. Varykhalov, J. Sánchez-Barriga, A. M. Shikin, C. Biswas, E. Vescovo, A. Rybkin, D. Marchenko, O. Rader, Electronic and Magnetic Properties of Quasifreestanding Graphene on Ni, Phys. Rev. Lett. 101, 157601 (2008).O. Rader, A. Varykhalov, J. S anchez-Barriga, D. Marchenko, A. Rybkin, A. M. ShikinIs There a Rashba, Effect in Graphene on 3d Ferromagnets? Phys. Rev. Lett. 102, 057602 (2009).

Graphene for spintronics: giant Rashba splitting due to hybridization with Au
D. Marchenko, A. Varykhalov, M. R. Scholz, G. Bihlmayer, E. I. Rashba, A. Rybkin, A. M. Shikin, O. Rader (unpublished)