Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 90: Graphene: Transport incl. Spin Physics and Magnetic Fields II
HL 90.2: Vortrag
Donnerstag, 29. März 2012, 17:15–17:30, ER 270
Does contact induced doping limit the measurable spin dephasing time in graphene non-local spin valves? — •Marc Drögeler1,2, Frieder Reichenzer1,2, Stefan Göbbels1,2, Frank Volmer1,2, Eva Maynicke1,2, Gernot Güntherodt1,2, and Bernd Beschoten1,2 — 1II. Institute of Physics, RWTH Aachen University, 52074 Aachen — 2JARA: Fundamentals of Future Information Technology, 52074 Aachen
With respect to spintronics, graphene has the advantage to consist of light atoms and, thus, exhibits negligible spin-orbit coupling and hyperfine interaction in isotopically pure material. This leads to long spin dephasing times with values predicted in the range of µs. The first spin transport measurements, however, revealed spin dephasing times in the range of a few hundred ps. In the meantime, values of 6.2 ns at 20 K [1] and 1.9 ns at room temperature [2] have been reported, which are still far below predicted values. A possible source of spin dephasing may arise from contact-induced carrier doping and consequential local electric fields in the graphene sheet. Here we use photo-current measurements to determine the contact induced doping in graphene-based non-local spin valves, which may be correlated to spin dephasing times as extracted from conventional Hanle spin precession measurements. Furthermore, we investigate the dependence of the photo-current on the polarization angle and helicity of the light.
This work has been supported by DFG through FOR 912.
[1] Han et al. Phys. Rev. Lett. 107, 047207 (2011).
[2] Yang et al. Phys. Rev. Lett. 107, 047206 (2011).