Magneto-electronic properties of graphene nanoribbons with various edge structures passivated by phosphorus and hydrogen atoms

Abstract

The electronic and magnetic structures of graphene nanoribbons (GNRs) with various edge structures passivated by P atoms are investigated systematically, and compared with H passivation as well. GNRs with the entire reconstructed Klein edge or armchair edge are found to be nonmagnetic regardless of P or H passivation. However, if the edge of GNRs is a mixture of zigzag edge and reconstructed Klein edge, they are nonmagnetic for H passivation but significantly magnetic for P passivation, which could be attributed to the "charge transfer doping" effect. And the corresponding magnetic device shows a noticeable negative differential resistance phenomenon and an excellent spin filtering effect under AP configuration, which originate from the special energy band structure. The GNRs with zigzag edge, reconstructed Klein edge, or mixed edge shapes are all metals in the nonmagnetic state regardless of the H or P atoms involved. The relationship between the energy gap and the width in armchair-edged GNRs by P passivation with a dimer structure also satisfies the 3p periodicity, but different in detail from the case of H passivation. The calculated edge formation energy indicates that P-passivated GNRs are energetically more favorable, suggesting that they can stably exist in the experiment.

Existence of multi-radical and closed-shell semiconducting states in post-graphene organic Dirac materials

“…However, for the remainder of the studied materials, with non-negligible spin polarisation, a sizeable band gap opens at the Dirac point, ranging from 1 eV (GY) to 2 eV (GDP). In line with these results, the correlation between radical centres with an AFM alignment of localised spins and the appearance of sizeable band gaps has been previously reported for nanoribbons of graphene 21 , 22 , 51 and GY 30 , 31 , as well as for isotropically strained graphene 27 . In all cases the gap opening can be rationalised by the breaking of the hexagonal symmetry of the system.…”

“…1b have been reported to have intrinsic localised multi-radical and quinoidal electronic states. However, for graphene, experimental and theoretical studies have shown that such localised states can be generated by: (i) nano-patterning 18 – 20 , (ii) cutting it into nanoribbons 18 , 21 , 22 , (iii) covalent grafting of molecules 23 or atoms 24 , 25 , (iv) inclusion of defects 26 , or (v) applying external strains 27 , 28 . Analogously, computational modelling has predicted similar states in α-graphyne (GY) upon application of strain 29 or by forming α-GY nanoribbons 30 , 31 .…”

Phagraphene nanoribbons: half-metallicity and magnetic phase transition by functional groups and electric field

“…To further tune or improve magnetic features of graphene nanoribbons, other commonly-used manners include defect engineering [9][10][11], heteroatom doping [12], edge modifications [13][14][15][16] and surface adsorptions [17]. However, the defectintroduced nanostructures usually lack geometrical stability.…”

Asymmetric passivation of edges: a route to make magnetic graphene nanoribbons

“…[2][3][4][5][6] It is well known that the ground state of ZGNRs is characterized by spin-polarized electronic states at two edges, which couple through the graphene backbone and result in an antiferromagnetic (AF) arrangement of spins on adjacent atomic sites with zero total magnetic moment. [7][8][9][10][11] In this regard, many works reported the electronic properties and chemical properties of the edge states of ZGNRs while the structure is modied by defects, [12][13][14][15] doping foreign atoms, [16][17][18][19][20][21] hydrogenation, [22][23][24][25][26][27][28][29][30] oxidation, 31 adsorption of some gas molecules [32][33][34][35] and external electric eld. [36][37][38] However, it remains a challenge to produce ferrimagnetic ZGNRs with modication of the structures.…”