1 research outputs found
Graphene based superconducting quantum point contacts
We investigate the Josephson effect in the graphene nanoribbons of length
smaller than the superconducting coherence length and an arbitrary width .
We find that in contrast to an ordinary superconducting quantum point contact
(SQPC) the critical supercurrent is not quantized for the nanoribbons
with smooth and armchair edges. For a low concentration of the carriers
decreases monotonically with lowering and tends to a constant minimum for
a narrow nanoribbon with . The minimum is zero for the
smooth edges but for the armchair edges. At higher
concentrations of the carriers this monotonic variation acquires a series of
peaks. Further analysis of the current-phase relation and the Josephson
coupling strength in terms of and the concentration of carriers
revels significant differences with those of an ordinary SQPC. On the other
hand for a zigzag nanoribbon we find that, similar to an ordinary SQPC,
is quantized but to the half-integer values .Comment: 8 pages, 5 figure