Switching effects in superconductor/ferromagnet/superconductor graphene junctions

Abstract

The Josephson effect in the superconductor/ferromagnet/superconductor (SFS) graphene Josephson junction is studied using the Dirac Bogoliubov-de Gennes (DBdG) formalism. It is shown that the SFS graphene junction drives 0—π transition with the increasing of p = h0L/vFħ, which captures the effects of both the exchange field and the length of the junction; the spin-down current is dominant. The 0 state is stable for p < pc (critical value pc ≈ 0.80) and the π state is stable for p > pc, where the free energy minima are at φg = 0 and φg = π, respectively. The coexistence of the 0 and π states appears in the vicinity of pc.

0– π transition induced by the barrier strength in spin superconductor Josephson junctions

“…[18][19][20][21][22][23] The charge supercurrent across the junction is mediated by the Andreev bound states formed by the electrons and holes inside the normal segment of the junction. [24][25][26][27][28][29][30][31] As an analogy of the conventional Josephson junction, the SSC Josephson junction can be achieved by a weak link between two SSCs. There are both the spin-conserved and the spinflip reflections at the normal-metal/SSC interface, [3] which are the counterparts of the normal reflection and the Andreev reflection at the normal-metal/superconductor interface, respectively.…”