Quantum Pumping In Graphene And Graphene-like Materials

We mainly investigate the property of adiabatic quantum pumping in graphene and grapheme-like honeycomb materials.In Chapter One, we make some introductions about the basic property of graphene, the concepts of spintronics and valleytronics, the principle of quantum pumping and research ambition of the dissertation.In Chapter Two, we make some introductions about the model and the method of computing, which including Dirac equation and scatter theory of quantum pumping.In Chapter Three, we use the theory of quantum pumping to study the spin current, valley current and charge current in graphene and graphene-like honeycomb materials. We investigate the property of adiabatic quantum pumping in graphene and graphene-like honeycomb crystal by cyclic modulation of the strain and potential.(1) We have found that we can generate pure spin current and pure valley current in graphene, meanwhile the charge current is zero;(2) We can also choose proper parameter to increase the magnitude of spin current and valley current.(3) We also found that with the magnitude of strain increases, the magnitude of valley current is decrease.(4) Finally, we applied an exchange field in graphene, we can generate the spin polarized current and valley polarized current, meanwhile the charge current is not zero.Finally, In Chapter four, we make summarize about the dissertation, making plans for the future research.