Spin transport and tunnel magnetoresistance in ferromagnetic graphene/Thue–Morse graphene superlattice double junction

• The conductance shows irregular oscillation.
• A defect peak appears in the conductance spectrum.
• The FG/TMGSL double junction possesses marked defect effect.
• The FG/TMGSL double junction has larger TMR.

We have theoretically investigated the spin transport properties and tunnel magnetoresistance of the double junction, which consists of the fifth-stage Thue–Morse graphene superlattice (TMGSL) or periodic graphene superlattice (PGSL) and three ferromagnetic graphene (FG) electrodes. The results indicate that the middle ferromagnetic graphene stripe can lead to obvious defect effect on the conductance. Meanwhile, the FG/TMGSL double junction possesses more marked defect effect when compared to the FG/PGSL double junction, along with larger and more irregular oscillation conductance and tunnel magnetoresistance.