Efficient spin injection into graphene through a tunnel barrier: overcoming the spin conductance mismatch

Employing first-principles calculations, we investigate efficiency of spin injection from a ferromagnetic (FM) electrode (Ni) into graphene and possible enhancement by using a barrier between the electrode and graphene. Three types of barriers, h-BN, Cu(111), and graphite, of various thickness (0-3...

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Bibliographic Details
Published in:arXiv.org 2014-11
Main Authors: Wu, Qingyun, Shen, Lei, Bai, Zhaoqiang, Zeng, Minggang, Yang, Ming, Huang, Zhigao, Feng, Yuan Ping
Format: Article
Language:English
Subjects:
Computational efficiency
Computing time
Copper
Efficiency
Electrical junctions
Electrodes
Electronic structure
Ferromagnetism
First principles
Graphene
Graphite
Mathematical analysis
Nickel
Resistance
Thickness
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Summary:Employing first-principles calculations, we investigate efficiency of spin injection from a ferromagnetic (FM) electrode (Ni) into graphene and possible enhancement by using a barrier between the electrode and graphene. Three types of barriers, h-BN, Cu(111), and graphite, of various thickness (0-3 layers) are considered and the electrically biased conductance of the Ni/Barrier/Graphene junction are calculated. It is found that the minority spin transport channel of graphene can be strongly suppressed by the insulating h-BN barrier, resulting in a high spin injection efficiency. On the other hand, the calculated spin injection efficiencies of Ni/Cu/Graphene and Ni/Graphite/Graphene junctions are low, due to the spin conductance mismatch. Further examination on the electronic structure of the system reveals that the high spin injection efficiency in the presence of a tunnel barrier is due to its asymmetric effects on the two spin states of graphene.
ISSN:2331-8422
DOI:10.48550/arxiv.1411.0779