Tunneling Negative Magnetoresistance via \delta Doping in a Graphene-Based Magnetic Tunnel Junction

We investigate the tunneling magnetoresistance via \delta doping in a graphene-based magnetic tunnel junction in detail. It is found that the transmission probability and the conductance oscillates with the position and the aptitude of the \delta doping. Also, both the transmission probability and the conductance at the parallel configuration are suppressed by the magnetic field more obviously than that at the antiparallel configuration, which implies a large negative magnetoresistance for this device. The results show that the negative magnetoresistance of over 300% at B=1.0 T is observed by choosing suitable doped parameters, and the temperature plays an important role in the magnetoresistance. Thus it is possible to open a way to effectively manipulate the magnetoresistance devices, and to make a type of magnetoresistance device by controlling the structural parameter of the \delta doping.