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Controlling the efficiency of spin injection into graphene by carrier drift

C. Józsa, M. Popinciuc, N. Tombros, H. T. Jonkman, and B. J. van Wees
Phys. Rev. B 79, 081402(R) – Published 10 February 2009

Abstract

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 nonlocal spin valve measurements in cobalt/aluminum-oxide/graphene structures with an injection efficiency as high as 18%, where electrical contact is achieved through relatively transparent regions in the oxide. This value is further enhanced to 31% by applying a dc current bias on the injector electrodes, which 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.

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  • Received 12 November 2008

DOI:https://doi.org/10.1103/PhysRevB.79.081402

©2009 American Physical Society

Authors & Affiliations

C. Józsa1, M. Popinciuc2, N. Tombros1, H. T. Jonkman2, and B. J. van Wees1

  • 1Physics of Nanodevices, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
  • 2Molecular Electronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands

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Issue

Vol. 79, Iss. 8 — 15 February 2009

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