The Investigation Of Doped Infinite Single Layer Graphene Nano Ribbon Based Parametric Pump And Spin Pump

Graphene is one of the most important two dimension materials in the field of science. The transport of quantumn pumped is the hot field of consensed matter physics. In this thesis, the electron pumping properties and electron spin pumping properities of pristine graphene ribbons and their doping behaviors by nitrogen atom or boron atom are studied. The thesis is organized as follow:In chapter 1, the investigation background of graphene and its band structure are introduced. In chapter 2, we give the tight binding method for mesoscopic system, the Green’s function approach, the transfer matrix technique, and the theory about adiabetic parametric pump and spin parametric pump. In chapter 3, the transmission coefficients, density of states and pumped current for different printine graphene ribbon are calculated, respectively. The relationship of them is analyzed theoretically, at the same, the effects of different doping are discussed in detail. The results show that the peak of current appears at peak position of DOS and the pumped current increases when increasing the pumping frequency, and the pumped current and the pumped phase have a relationship of sine when pumping voltage is small, and the sinusoidal relationship will be destroyed while increasing the concentration of doping. In chapter 4, the spin pumped current of zigzag graphene is studied, and the effects of doping are analyzed. The results show that periodical doping has obvious influence to the spin current. Finally, in chapter 5, some conclusions are given.