Straintronics in graphene nanoribbons

TL;DR

This paper investigates how uniaxial strain affects electronic transport and negative differential resistance in zigzag graphene nanoribbons, revealing strain-dependent switching behavior and symmetry breaking that could enable nano-electromechanical devices.

Contribution

It provides a detailed analysis of strain effects on charge transport and NDR in ZGNRs using non-equilibrium Green's function formalism, highlighting potential for strain-controlled nano-switches.

Findings

Oblique strain breaks parity conservation, reducing on-off ratio.

Tensile strain increases the on/off current ratio.

Oblique strain induces transverse currents and symmetry breaking.

Abstract

The interplay between uniaxial strain and charging effects in zigzag graphene nanoribbons (ZGNR) is investigated by using non-equilibrium Green's function formalism. The I-V characteristic curves and especially negative differential resistance (NDR) induced by some quantum selection rules are affected by the type, strength and also direction of the applied strain. For the oblique strain, the parity conservation fails while it conserves at the longitudinal and transverse strains. Therefore, in the oblique strain, on-off current ratio drastically decreases in compared to the un-strained case. For the tensile strain along the ribbon axis, $ I_{on}/I_{off} $ ratio increases while for the compressive strain, NDR will be gradually disappeared. This property can be useful for nano-electromechanical switch in which by changing the tensile to compressive strain, current switches between its on and off-current state. Furthermore, under influence of the oblique uniaxial strain, the geometry symmetry of charge accumulation as well as bond local currents will be broken across ZGNR giving rise to a transverse current between upper and lower edges of the nanoribbon. This transverse current would be enhanced by the strain strength where gradient of charge density would be maximum at the off-current state.