Abstract

We study the quantum transport properties of graphene nanoribbons (GNRs) with a different edge doping strategy using density functional theory combined with nonequilibrium Green’s function transport simulations. We show that boron and nitrogen edge doping on the electrodes region can substantially modify the electronic band structures and transport properties of the system. Remarkably, such an edge engineering strategy effectively transforms GNR into a molecular spintronic nanodevice with multiple exceptional transport properties, namely: (i) a dual spin filtering effect (SFE) with 100% filtering efficiency; (ii) a spin rectifier with a large rectification ratio (RR) of 1.9 ×; and (iii) negative differential resistance with a peak-to-valley ratio (PVR) of 7.1 ×. Our findings reveal a route towards the development of high-performance graphene spintronics technology using an electrodes edge engineering strategy.

Highlights

  • High-Performance GrapheneNanostructures and nanodevices with unusual spin-transport properties, such as dual spin filtering [1,2], magnetoresistance effect [3], molecular rectification [4] and negative differential resistance (NDR) [5], have attracted tremendous research interests in recent years due to their enormous potential as the building blocks in spintronics technology.Two-dimensional (2D) materials, such as graphene, have been extensively studied due to their exceptional physical and transport properties [6–9]

  • Our results show that the B/N edge doping provides an efficient tool to tune the electronic band structures of STGNRs which sensitively influences the spintronic transport properties of a source–channel–drain nanodevice structures

  • The transmission behavior can be understood from the energy level and the degree of delocalization of the frontier molecular orbitals (FMOs), especially the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) which are near to the Fermi level

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Summary

Introduction

Nanostructures and nanodevices with unusual spin-transport properties, such as dual spin filtering [1,2], magnetoresistance effect [3], molecular rectification [4] and negative differential resistance (NDR) [5], have attracted tremendous research interests in recent years due to their enormous potential as the building blocks in spintronics technology. Zigzag-edged graphene nanoribbons (ZGNRs) are promising due to the presence of electric field effect tuning of the spin-polarized edge states [20,21]. The. ZGNRs can be further designed into nanodevices with unusual transport behaviors, such as thermal regulation [22], spin filtering [7], spin diode [21] and NDR [23] effects, using a plethora of strategies, including edge modifications [24,25], doping [26,27] and a applying magnetic field [28]. Our results show that the B/N edge doping provides an efficient tool to tune the electronic band structures of STGNRs which sensitively influences the spintronic transport properties of a source–channel–drain nanodevice structures. Our findings concretely establish the edge-doping strategy as a potential promising route towards the design and development of STGNRbased nanodevices, such as molecular spin diode, random access memory cells and fast switching devices

Computational Details
Spin-Resolved Tunneling Current, Rectification Ratio and Negative Differential
Electronic Band Structures of the Electrodes and Spin-Dependent Transmission Spectra
The Molecular Projected Self-Consistent Hamiltonian(MPSH), Spin Polarized Density, and Transmission Pathway
Electron Energy and Bias Voltage Dependence of the Spin-Resolved Transmission Spectrum
Conclusions

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