Hartman effect and spin precession in graphene.
R. A. Sepkhanov M. V. Medvedyeva C. W. J. Beenakker
posted in Condensed Matter on Thursday, October 15th, 2009
Spin precession has been used to measure the transmission time \tau over a distance L in a graphene sheet. Since conduction electrons in graphene have an energy-independent velocity v, one would expect \tau > L/v. Here we calculate that \tau < L/v at the Dirac point (= charge neutrality point) in a clean graphene sheet, and we interpret this result as a manifestation of the Hartman effect (apparent superluminality) known from optics.
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