Transport Properties Of Dirac Electrons On The Surface Of A Topological Insulator

A topological insulator is a material that behaves as an insulator in its intorior while permitting the movement of charges on its boundary. We consider the effect of the spin, the movement of charges on the surface of a topological insulator obey Dirac equation with a small mass, we can obtain the wave function of the electrons in the barriers and magnetic field. Due to the continuity of the wave function and Bloch theorem, matching boundury conditions on the wave function, we can attain the band structures and transport features of Dirac eletrons in the barriers and magnetic field on the surface of a topological insulator. The following are the main contents and results:(1) The transport properties in double barriers with a magnetic field on the surface of a topological insulator are investigated. It is shown that the electron exhibits the resonance transmission through double barriers except for the incidence perpendicular to barrier plane and the electron transmission cab be partly controlled by the field magnitude along Y axis or electron energy. Corresponding conductance changes symmetrically with the magnetic field. The resonance transmission is observed when the electron energy increases and cut-off energy depend on the magnitude of magnetic field along Y axis.(2) The band structures of Dirac electrons in one-dimensional periodic field on the surface of a topological insulator are investigated. The pericdic field is made up of square barriers and magnetic field. A new Dirac point will be observed, when the eletrons transit. The locations of the new Dirac point are determined by the electron energy, the heights of the potentials and the magnetic field. We can change the band structures of Dirac electrons and move the locations of Dirac points by modifing the heights of the potentials ans the magnetic field. So we can modulation transport features of Dirac eletrons by changing the parameters of the superlattices.