Controlling the efficiency of spin injection into graphene by carrier drift

Electrical spin injection from ferromagnetic metals into graphene is hindered by the impedance mismatch between the two materials. This problem can be reduced by the introduction of a thin tunnel barrier at the interface. We present room temperature non-local spin valve measurements in cobalt/alumin...

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Bibliographic Details
Published in:arXiv.org 2008-11
Main Authors: Józsa, C, Popinciuc, M, Tombros, N, Jonkman, H T, van Wees, B J
Format: Article
Language:English
Subjects:
Alternating current
Aluminum oxide
Bias
Drift
Electric contacts
Ferromagnetism
Graphene
Pinholes
Spin valves
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Summary:Electrical spin injection from ferromagnetic metals into graphene is hindered by the impedance mismatch between the two materials. This problem can be reduced by the introduction of a thin tunnel barrier at the interface. We present room temperature non-local spin valve measurements in cobalt/aluminum-oxide/graphene structures with an injection efficiency as high as 25%, where electrical contact is achieved through relatively transparent pinholes in the oxide. This value is further enhanced to 43% by applying a DC current bias on the injector electrodes, that causes carrier drift away from the contact. A reverse bias reduces the AC spin valve signal to zero or negative values. We introduce a model that quantitatively predicts the behavior of the spin accumulation in the graphene under such circumstances, showing a good agreement with our measurements.
ISSN:2331-8422
DOI:10.48550/arxiv.0811.2960