Tuning the magnetic and electronic properties of bilayer graphene nanoribbons on Si(001) by bias voltage

Abstract

We report on a systematic study of bias-voltage-induced modulation of magnetic and electronic properties of bilayer zigzag graphene nanoribbons ͑Z-GNRs͒ on Si͑001͒ substrate by first-principles calculations. We show that the intrinsically nonmagnetic bilayer Z-GNRs exhibit magnetic ordering on the top layer while the bottom layer serves as a nonmagnetic buffer layer when adsorbed on the substrate. Interestingly, the adsorbed bilayers display distinct ribbon-width-dependent magnetoelectric effect under bias voltages. The magnetoelectric coefficient oscillates with increasing ribbon width, which arises from an interesting interplay of the interaction of the bottom ribbon layer with the substrates and the decay length of the localized edge states in Z-GNRs. Moreover, our calculations reveal that the electronic band gap of the top ribbon layer also can be effectively modulated by the applied bias voltage, which can lead to a semiconductor-to-metal transition in the top magnetic semiconductor layer. These results provide insights into the intriguing behaviors of Z-GNRs on substrates and raise the prospects of developing an innovative path toward graphene-based electronic and spintronic devices by integrating the emerging nanoscale graphene systems with existing silicon technology.

Electronic properties of graphene-based bilayer systems

“…The effect of silicone substrate on nanoribbon electron properties was investigated by Z. Zhang et al in Ref. [179]. According to this DFT study, the carbon atoms at the edges of the nanoribbon bottom layer form covalent Si-C bonds to the silicone atoms of the substrate.…”

“…[18]). Likewise, AB bilayer zigzag nanoribbons were actively researched in connection with their magnetic properties [157,158,179,180]. At the bilayer edge one might expect that both layers would be magnetized.…”

Generation of coherent radiation by magnetization reversal in graphene

“…Examples of these nanomolecules are: C 56 H 22 , C 64 H 23 , C 56 H 24 , C 64 H 25 , and C 64 H 27 . Zigzag edges can show magnetism in bilayer graphene [34]. Organic substrates on graphene can be magnetized [35].…”

Band structure and optical absorption in multilayer armchair graphene nanoribbons: A Pariser-Parr-Pople model study

“…8 While numerous theoretical studies of the electronic structure and related properties of the mono-layer GNRs exist, 10 relatively fewer calculations on bilayer and multilayer-GNRs have been performed. [11][12][13][14][15][16][17][18][19][20] Recently, gated bilayer graphene has attracted a great deal of attention in the experimental, [21][22][23][24][25] as well as theoretical communities. [26][27][28][29][30] The energy gap in bilayer graphene, in the presence of a transverse electric field, has been found to be tunable over a wide range of values (up to 250 meV).…”