Confinement and Waveguide Effects of Quantum Wires Formed in Graphene by Strain

Confinement of electrons in graphene to make devices has proven to be a challenging task. Fortunately, the mechanical flexibility of graphene raises the possibility of using strain to alter its properties. Recent transport measurements on graphene nanowires created by linearly-shaped strained folds encapsulated by boron nitride reveal Coulomb blockade signatures, indicating charge confinement effects [1]. Here, we model the system within the continuum Dirac formalism with the effect of strain included as a pseudo-magnetic field. Apart from extended scattering states similar to those in pristine graphene, the fold supports different types of bound states distinguished by their distinctive dispersion, which can contribute to the confinement effect observed experimentally. Possible effects of the encapsulation process, which may modify the geometry of the folded structure, as well as the crystalling orientation of the fold are examined. Our results show that confinement is robust against variations in the geometry but vanishes continuously as the armchair orientation is reached.
[1] Y. Wu et al, Submitted to Nano Lett.