Dynamical Band-Engineering of Spin-Polarized Edge States in Nanostructures

The ability to engineer the band structure and electronic properties of nanostructures is a key step for potential applications ranging from spintronic devices to quantum information. We present theoretical results on the electronic and transport properties of a normal insulator, in form of a zigzag ribbon based on the graphene-like Kane-Mele model subjected to circularly polarized radiation. It is found that chiral edge-states can be induced in the band gap of the quasi-energy spectra under periodic driving. More interestingly, for appropriate parameters, there exists a single chiral edge state at each boundary of the sample. As a result, the conductance shows plateau structure with the step height e$^{2}$/h as we increase the ac field intensity. These observations may find their potential applications for high-efficiency non-magnetic spin injection which can be readily tuned by modulating an external ac field. \\[4pt] [1] B. H. Wu, Q. Liu, X.-Y. Jiang, and J. C. Cao, Appl. Phys. Lett. 100, 203106 (2012).