Enhancement of weak localization for nitrogen-doped graphene by short range potentials

We have prepared pristine graphene and nitrogen-doped graphene on copper foils by chemical vapor deposition. Compared with the pristine graphene, an increased disorder in nitrogen-doped graphene was confirmed by Raman spectra studies. Temperature dependent Hall resistances and magnetoresistances were measured for both samples. The carrier densities can be extracted from the experimental datum. Abrupt decreases of magnetoresistances near zero magnetic field strongly suggest weak localization effects for both samples. Furthermore, more obvious decreases of magnetoresistances near zero magnetic field and valleys at higher magnetic fields were observed due to an enhancement of weak localization for nitrogen-doped graphene. The whole field dependence of magnetoresistance at different temperatures can be well fitted by a revised McCann model. By defining characteristic magnetic fields, visual phase diagrams were obtained. In addition, larger weak localization area was found for nitrogen-doped graphene than the one for pristine graphene. Our results manifest that an increased elastic intervalley scattering which comes from the increased disorder with short range potentials should account for the expected enhancement of the weak localization for nitrogen-doped graphene.