Intrinsic Half-Metallicity in Modified Graphene Nanoribbons

Abstract

We perform first-principles calculations based on density functional theory to study quasi onedimensional edge-passivated (with hydrogen) zigzag graphene nanoribbons (ZGNRs) of various widths with chemical dopants, boron and nitrogen, keeping the whole system isoelectronic. Gradual increase in doping concentration takes the system finally to zigzag boron nitride nanoribbons (ZBNNRs). Our study reveals that, for all doping concentrations the systems stabilize in antiferromagnetic ground states. Doping concentrations and dopant positions regulate the electronic structure of the nanoribbons, exhibiting both semiconducting and half-metallic behaviors as a response to the external electric field. Interestingly, our results show that ZBNNRs with terminating polyacene unit exhibit half-metallicity irrespective of the ribbon width as well as applied electric field, opening a huge possibility in spintronics device applications.Nanomaterials of carbon, like nanotubes, fullerenes, etc., have been of great interest in condensed-matter and material science because of their novel low-dimensional properties [1,2]. Over past few decades, cutting edge research has been carried out for advanced device integration, exploring the electronic and mechanical properties of these systems. The recent addition in this journey is graphene: a strictly two-dimensional flat monolayer of carbon atoms tightly packed into a honeycomb lattice [3,4]. Since its innovation [5,6,7], it has made possible the understanding of various properties in two dimensions, by simple experiments and has opened up huge possibilities for electronic device fabrications [8,9,10]. A large number of theoretical and experimental groups all over the world have gathered on this two dimensional platform to search for the "plenty of room" at this reduced dimension [11].Electronic properties of low dimensional materials are mainly governed by their size and geometry. Recent experimental sophistications permit the preparation of finite size quasi one dimensional graphene, named as graphene nanoribbons (GNRs) of varying widths, either by cutting mechanically exfoliated graphenes and patterning by lithographic techniques [12,13] or by tuning the epitaxial growth of graphenes [14,15]. Different geometrical terminations of the graphene monolayer give rise to two different edge geometries of largely varying electronic properties, namely, zigzag and armchair graphene. Several theoretical models, e.g., tight-binding model within Schrodinger [16,17,18], Dirac formalism for mass less fermions [19,20,21], density functional theory (DFT) etc. have been applied to explore the electronic and band structure properties of GNRs. There exists a few many-body studies, exploring the electronic and magnetic properties of these systems [22,23].DFT studies suggest that, the anti-ferromagnetic quasi one-dimensional (1D) zigzag edge graphene nanoribbons (ZGNRs) show half-metallicity at a finite external elec- tric field across the ribbon width within both local density approximation (LDA) [24] and g...

First-principles study of the electrical and lattice thermal transport in monolayer and bilayer graphene

“…Pop et al [43] have mentioned that any surplus residue from sample fabrication or any form of disorder will reduce the thermal conductivity further. There have been many experimental [44][45][46][47][48][49] and theoretical [50][51][52] reports to show the formation of a band gap by doping graphene with boron nitride. Similarly there are reports to show the formation of band gaps in bilayer graphene [53][54][55] when under the influence of an electric field.…”

Symmetry-dependent transport properties and bipolar spin filtering in zigzagα-graphyne nanoribbons

“…So far, a number of theoretical schemes have been proposed in this direction. For example, it is shown that ZGNR becomes half-metal by applying external electric field 2,9 or chemical modification [10][11][12] , which can be utilized for generation of spin polarized current. Also, bipolar spin-filtering and larger magnetoresistance (MR) effects have been predicted in a ZGNR-based spin-valve device, in which ZGNR is connected to two electrodes and external magnetic fields are applied to these electrodes with different magnetization configurations [13][14][15][16] .…”

Ferromagnetism and Half‐Metallicity in a High‐Band‐Gap Hexagonal Boron Nitride System

“…[19] Ferromagnetism and half-metallicity was successfully introduced in graphene and h-BN by aspecific patterned hydrogenation process. [20][21][22][23][24] However,i ti se xtremely difficult to controlp atterned hydrogenation. As ar esult,h ydrogenationc an occur in ar andom manner on the host structure.…”