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Magnetotransport in Modulated Graphene by Rubina Nasir
Submitted to the Department of Physics on 25 June 2012, in partial ful…llment of the requirements for the degree of Doctor of Philosophy

Recent experimental as well as theoretical works have shown that it is possible to create periodic, electric as well as magnetic, potentials in graphene. The e¤ects of these potentials on charge carriers in graphene leads to novel physical e¤ects with important consequences for transport. Whereas a strong periodic potential can lead to new Dirac points in the band structure of graphene, a weak periodic potential along with a perpendicular magnetic …eld B introduces a new length scale, period of modulation, in the system in addition to the cyclotron diameter at the Fermi energy. Commensurability of these two length scales leads to new observable physical e¤ects. These e¤ects were observed earlier in transport studies in conventional 2DEG systems realized in semiconductor heterostructures. Our aim is to study these e¤ects in a graphene monolayer in order to highlight the similarities and di¤erences in the two systems, conventional 2DEG and graphene. Therefore, in this thesis we have carried out a detailed investigation of the electrical magnetotransport properties of a one-dimensional weakly modulated graphene monolayer. It is found that the periodic modulation broadens the sharp Landau Levels into bands and they start oscillating with B. The electronic conduction in this system can take place through either di¤usive scattering or collisional scattering o¤ impurities. Both these contributions to the electronic transport are taken into account in this work. In addition to the appearance of commensurability oscillations in both the collisional and di¤usive contributions, we …nd that Hall resistance also exhibits commensurability oscillations. Furthermore, the period…...

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