Controlling the efficiency of spin injection into graphene by carrier drift

C. Jozsa*, M. Popinciuc, N. Tombros, H. T. Jonkman, B. J. van Wees

*Corresponding author for this work

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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.

Original languageEnglish
Article number081402
Pages (from-to)081402-1-081402-4
Number of pages4
JournalPhysical Review. B: Condensed Matter and Materials Physics
Issue number8
Publication statusPublished - Feb-2009


  • aluminium compounds
  • carbon
  • cobalt
  • electrical contacts
  • ferromagnetic materials
  • nanostructured materials
  • spin valves

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