Perfect switching of the spin polarization in a ferromagnetic gapless graphene/superconducting gapped graphene junction

With the fabrication of gapped graphene, interest in the tunneling spectroscopy in graphene-based FG/SG junctions in which one side consists of a gapless ferro-magnetic graphene (FG) and the other side, of a gapped superconducting graphene (SG) has arisen. The carriers in the gapless (gapped) graphene are 2D relativistic particles having an energy spectrum given by E = ℏ 2 v F 2 k 2 + ( mv F 2 ) 2 (where mv F 2 is the gap and v F is the Fermi velocity). The spin currents in this FG/SG junction are obtained within the framework of the extended Blonder–Tinkham–Klapwijk (BTK) formalism. The effects of the superconducting energy gap in SG, of the gap mv F 2 which opened in the superconducting graphene, of the exchange field in FG, of the spin-dependent specular Andreev reflection, of the effective Fermi energy ( E FF ) of FG and of the bias voltage across the junction ( V ) are simulated. It is seen that by adjusting E FF or V , the spin polarization (defined as SP(%) = 100% × ( G ↑ − G ↓ )/( G ↑ + G ↓ )) can be switched from a pure spin up (SP = +100%) state to pure spin down (SP = −100%) state.