Sub-gap transport in graphene-based double junctions

Based on the transfer-matrix method, the charge transport properties of the electrons through a ballistic graphene-based quantum tunneling junctions with the inhomogeneous spin–orbit interactions (SOIs) have been investigated theoretically. In sharp contrast to the conventional normal metal/2D electron gas/normal metal junctions and the graphene-based double junctions with a big incident energy, the normal transmission coefficient monotonically decreases with the length of middle region in the limit of a vanishing Rashba SOI term. While only the Rashba SOI exists, the maximum of the sum of the transmission coefficient equates to about 0.5, only one half of the value for the case of a big incident energy. It is also found that the conductance can be dominated by the incident energy and the SOI strength. It is anticipated to apply such a phenomenon to design the spin-polarized electron devices based on the graphene materials.