Magnetic, Electronic and Thermal Properties of Graphene Monolayer رسالة دكتوراة

Abstract

In this thesis, MATLAB program was used to analyze the electronic, thermal and magnetic properties of gapless and gapped graphene under an external perpendicular magnetic field. The Landau levels associated with the presence of external magnetic field of non-gapped and gapped graphene were plotted. In addition, band gap effects on the density of states of graphene was studied. The symmetry of Landau levels and density of states between conduction and valance bands are valid for both gapped and gapless graphene monolayer. At T= 0.3K the oscillationsin Fermi energy with magnetic field strength are more pronounced compared to that result at higher temperature (T= 4K). The number of oscillation at specific temperature depends only on the electron concertation and not on the energy band gap value. Several thermodynamic and magnetic quantities were studied as a function of both magnetic field strength and temperature. The introduction of band gap shifts the Schottky anomaly peak toward lower temperatures and higher specific heat values. At constant temperature, the entropy of gapped graphene versus magnetic field increases with increasing the band gap. Moreover, the Magneto Caloric Effect in both gapless and gapped graphene was plotted and analyzed in terms of the change in the entropy(-S). The coexistence of different types of magnetic states is verified by the observed maxima in the magnetization of graphene. Making it potentially useful in magnetic memory storage and magnetic switching applications.