First-principles study of spin-dependent transport through graphene/BNC/graphene structure

Tadashi Ota,Tomoya Ono

doi:10.1186/1556-276x-8-199

Abstract

First-principles study on the electronic structure and transport property of the boron nitride sheet (BNC) structure, in which a triangular graphene flake surrounded by a hexagonal boron nitride sheet, is implemented. As the graphene flake becomes small and is more isolated by the boron nitride region, the magnetic ordering of the flake increases. When the BNC structure is connected to the graphene electrodes, the spin-polarized charge-density distribution appears only at the triangular graphene flake region, and the electronic structure of the graphene electrode is not spin polarized. First-principles transport calculation reveals that the transport property of the BNC structure is spin dependent.

Highlights

One of the key factors in the field of spintronics is the spin filter effect, which plays a fundamental role as the spin-polarized current source in devices such as spinfield-effect transistors and single solid-state qubits
In the previous study [7], we investigated the electronic structure and transport property of the BNC structures proposed by Okada et al [6] using first-principles calculations based on density functional theory [8] and revealed that the electron transport property of the BNC structure is spin dependent
By comparing the other BNC structures investigated in a previous study [7], where the boron and nitrogen atoms are placed at opposite positions and the number of nitrogen atoms is larger than that of boron atoms, we found that the present BNC structures exhibit a similar relationship between the size of the graphene flake and magnetic moment

Summary

Introduction

One of the key factors in the field of spintronics is the spin filter effect, which plays a fundamental role as the spin-polarized current source in devices such as spinfield-effect transistors and single solid-state qubits. The carbon-related nanostructures have recently been fabricated experimentally and explored theoretically to clarify magnetic ordering mainly in the zigzag edge of graphene [1,2,3]. These nanostructures are very attractive to the spin filter materials due to the remarkable long-spin coherence distance and high carrier mobility. If the small carbon flakes with a zigzag edge surrounded by an insulator have ferromagnetic groundstate electronic structures, this situation of carbon atoms resembles closely that of the quantum dots mentioned above. Okada et al [6] studied the electronic structure of the two-dimensional triangular graphene flake surrounded by a hexagonal boron nitride sheet, which is

Methods

Results

Conclusion