Strain-induced 0-π transition in a zigzag graphene nanoribbon Josephson junction

We study theoretically the supercurrent through a superconductor/ferromagnetic zigzag graphene nanoribbon/superconductor junction by the Matsubara Green function method. The transformation of the supercurrent between the 0 and pi states is remarkably realized in this Josephson junction by the combination of the uniaxial strain and gate-controlled barrier potential. Such strain-induced 0-pi transition is found to result from the dependence of the effective Fermi velocity on the uniaxial strain in the graphene nanoribbon modulated by mechanical approaches. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3571280]