Electrically tunable exchange splitting in bilayer graphene on monolayer Cr${}_2$X${}_2$Te${}_6$ with X=Ge, Si, and Sn

Abstract

We investigate the electronic band structure and the proximity exchange effect in bilayer graphene on a family of ferromagnetic multilayers Cr${}_2$X${}_2$Te${}_6$, X=Ge, Si, and Sn, with first principles methods. In each case the intrinsic electric field of the heterostructure induces an orbital gap on the order of 10 meV in the graphene bilayer. The proximity exchange is strongly band dependent. For example, in the case of Cr${}_2$Ge${}_2$Te${}_6$, the low-energy valence band of bilayer graphene has exchange splitting of 8 meV, while the low energy conduction band's splitting is 30 times less (0.3 meV). This striking discrepancy stems from the layer-dependent hybridization with the ferromagnetic substrate. Remarkably, applying a vertical electric field of a few V/nm reverses the exchange, allowing us to effectively turn ON and OFF proximity magnetism in bilayer graphene. Such a field-effect should be generic for van der Waals bilayers on ferromagnetic insulators, opening new possibilities for spin-based devices.

14 pages, 7 figurs, 1 table

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• Magnetic proximity in a van der Waals heterostructure of magnetic insulator and graphene
• Swapping Exchange and Spin-Orbit Coupling in 2D van der Waals Heterostructures
• Twist- and gate-tunable proximity spin-orbit coupling, spin relaxation anisotropy, and charge-to-spin conversion in heterostructures of graphene and transition-metal dichalcogenides
• Magnetic polaron and antiferro-ferromagnetic transition in doped bilayer CrI${}_3$
• Optically Probing Tunable Band Topology in Atomic Monolayers
• Engineering Proximity Exchange by Twisting: Reversal of Ferromagnetic and Emergence of Antiferromagnetic Dirac Bands in Graphene/Cr${}_2$Ge${}_2$Te${}_6$
• Bilayer graphene encapsulated within monolayers of WS${}_2$ or Cr${}_2$Ge${}_2$Te${}_6$: Tunable proximity spin-orbit or exchange coupling
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• Proximity spin-orbit and exchange coupling in ABA and ABC trilayer graphene van der Waals heterostructures
• Heterostructures of graphene and topological insulators Bi${}_2$Se${}_3$, Bi${}_2$Te${}_3$, and Sb${}_2$Te${}_3$
• Antiferromagnetic spin valve from heterostructure of two-dimensional hexagonal crystals
• Single and bilayer graphene on the topological insulator Bi${}_2$Se${}_3$: Electronic and spin-orbit properties from first principles
• Chiral Majorana fermions in graphene from proximity-induced superconductivity
• Electrically Controllable van der Waals Antiferromagnetic Spin Valve
• Proximity-induced diversified magnetic states and electrically-controllable spin polarization in bilayer graphene: Towards layered spintronics
• Hydrostatic pressure control of the spin-orbit proximity effect, spin relaxation, and thermoelectricity in a phosphorene-WSe${}_2$ heterostructure
• Proximity-enabled control of spin-orbit coupling in phosphorene symmetrically and asymmetrically encapsulated by WSe${}_2$ monolayers
• Electronic and Spin-Orbit Properties of hBN Encapsulated Bilayer Graphene
• Angular dependence of the interlayer coupling at the interface between two dimensional materials 1T-PtSe${}_2$ and graphene
• Valley-Polarized Quantum Anomalous Hall Phase in Bilayer Graphene with Layer-Dependent Proximity Effects