Ferromagnetic order induced on graphene by Ni/Co proximity effects

Abstract

We build a tight-binding Hamiltonian describing Co/Ni over graphene, contemplating ATOP (a Co/Ni atom on top of each Carbon atom of one graphene sublattice) and HCP (one Co/Ni atom per Graphene plaquette) configurations. For the ATOP configuration the orbitals involved, for the Co/Ni, are the $d_{z^2-r^2}$ which most strongly couple to one graphene sublattice and the $d_{xz}$, $d_{yz}$ orbitals that couple directly to the second sublattice site. Such configuration is diagonal in pseudo-spin and spin space, yielding electron doping of the graphene and antiferro-magnetic ordering in the primitive cell in agreement with DFT calculations. The second, HCP configuration is symmetric in the graphene sublattices and only involves coupling to the $d_{xz}$, $d_{yz}$ orbitals. The register of the lattices in this case allows for a new coupling between nearest neighbour sites, generating non-diagonal terms in the pseudo-spin space and novel spin-kinetic couplings mimicking a spin-orbit coupling generated by a magnetic coupling. The resulting proximity effect in this case yields ferromagnetic order in the graphene substrate. We derive the band structure in the vicinity of the K points for both configurations, the Bloch wavefunctions and their spin polarization.

References in corpus (5)

• Doping graphene with metal contacts
• The electronic properties of bilayer graphene
• Proximity-induced ferromagnetism in graphene revealed by anomalous Hall effect
• Spin Orbit Coupling in Graphene Induced by Heavy Adatoms with Electrons in the Outer-Shell $p$ Orbitals
• Gate-Tunable Exchange Coupling Between Cobalt Clusters on Graphene

Cited by in corpus (6)

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• Rashba spin-orbit interaction enhanced by graphene in-plane deformations
• Photoprotected spin Hall effect on graphene with substrate induced Rashba spin-orbit coupling