Modulation of external electric field on surface states of topological insulator Bi2Se3 thin films

What is it about?

We study surface band structure and topological phase transition for Bi2Se3 thin films under an external electric field. It is demonstrated that an electric field can close or reopen a gap for surface states. We also study the spin-dependent transport property through an interface junction constructed by the film. Interestingly, the opacity and transparency of spin-down Dirac fermions through the junction can be modulated by the electric field.

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Why is it important?

we design a simply way to control the electronic spin and transport in a topological insulator junction. Due to the Rashba spin-splitting, spin-down Dirac fermions can be totally reflected as photons at the interface, and the total reflection angle can be modulated from 0 to pi/2 by modulating an electric field. However, the spin-up fermions can always penetrate the interface of the junction. These features may pave a simple way for potential application of spintronic devices.