Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 22: Graphene 2 (Joint Session with TT)

HL 22.3: Talk

Tuesday, March 23, 2010, 10:00–10:15, H21

Spin injection in graphene spin valve devices via thin MgO barriers — •Tsung-Yeh Yang¹, Julia Samm¹, Marc Drögeler¹, Sebastian Blaeser¹, Frank Volmer¹, Mihaita Popinciuc¹, Jayakumar Balakrishnan², Ahmet Avsar², Manu Jaiswal², Mingang Zheng², Bernd Beschoten¹, Barbaros Oezyilmaz², and Gernot Güntherodt¹ — ¹II. Physikalisches Institut, RWTH Aachen University, Templergraben 55, 52056 Aachen, Germany — ²Department of Physics, National University of Singapore, 2 Science Drive 3 Singapore 117542

We report all-electrical spin transport measurements in non-local spin valve structures on graphene at room temperature. The graphene flakes were deposited on Si/SiO₂ substrates by mechanical exfoliation. The application of a back gate voltage allows for continuous control of the charge carrier type and density. Using ferromagnetic Co electrodes, efficient spin injection/detection was realized via thin MgO layers introduced between Co and graphene. Spin valve and Hanle spin precession measurements were performed for various charge carrier densities. The measurements at room temperature reveal the charge carrier mobilities of 4-5x10³ cm²/Vs and spin relaxation lengths of about 3 micrometers in the metallic conduction regime. Temperature dependent measurements of the Co/MgO/graphene contacts resistances indicate that the thin MgO layers behave as tunnel barriers.

This work is supported by DFG through FOR 912.