Observation of different charge transport regimes and large magnetoresistance in graphene oxide layers. (August 2015)

• Record Type: Journal Article
• Authors: Vianelli, A.; Candini, A.; Treossi, E.; Palermo, V.; Affronte, M.
• Is Part Of: Carbon. Volume 89(2015)
• Page Start: 188
• Page End: 196
• Publication Date: 2015-08
• Subjects: Carbon -- Periodicals; Carbone -- Périodiques; Koolstof; Toepassingen; Electronic journals; 546.681
• DOI: 10.1016/j.carbon.2015.03.019
• Languages: English
• ISSNs: 0008-6223

Abstract

Abstract: We report a systematic study on charge transport properties of thermally reduced graphene oxide (rGO) layers, from room temperature to 2 K and in presence of magnetic fields up to 7 T. The most conductive rGO sheets follow different transport regimes: at room temperature they show an Arrhenius-like behavior. At lower temperature they exhibits a thermally activated behavior with resistance R following a R = R 0 exp( T 0 / T ) p law with p = 1/3, consistently with 2D Mott Variable Range Hopping (VRH) transport mechanism. Below a given temperature Tc, we observe a crossover from VHR to another regime, probably due to a shortening of the characteristic lengths of the disordered 2D system. The temperature Tc depends on the reduction grade of the rGO. Magnetoresistance Δ R / R of our rGO films shows as well a crossover between positive and negative and below liquid He temperature Δ R / R reaches values larger than ∼–60%, surprisingly high for a – nominally – non magnetic material.