Design of strain-engineered quantum tunneling devices for topological surface states

Strain-dependent charge and spin transport on a topological insulator (TI) surface are investigated by combining first-principles calculations with quantum tunneling theory. It is shown that the Dirac point of helical surface states can be significantly shifted by applying compressive uniaxial strain. As an example of strain engineering applications based on this effect, a strain-induced quantum tunneling nanostructure is designed, where the tunneling conductance and the spin texture of surface states can be sensitively modulated by strain. Our work suggests that various local strain patterns can be integrated to manipulate surface states in all-TI-based spintronic nanodevices. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3699023]