Quasi-linear and Plateaus-like Tunneling Magnetoresistance in Graphene-based Tunable Magnetic Barrier Nanostructures

Abstract

The effect of electrostatic and magnetic vector potentials pattern on electrical properties and the tunneling magnetoresistance in graphene junction with periodic magnetic vector potentials are theoretically investigated using the transfer matrix method. The magnetic structure on graphene can control the direction of the magnetizations which correspond to the parallel and anti-parallel (AP) configurations. In AP magnetic structures with the applied gate voltage pattern, USUBA/SUB (U₁ = U₂), the shift of the conductance-peak position as a function of Fermi energy. The peak corresponds to resonant tunneling, where the incidence energy of the tunneling electron equals the confinement energy, and the conductance peak decrease approximately linearly with increasing electrostatic potential. The peak position occurs at ESUBF/SUB = 0.5U where it is shifted to higher Fermi energy with higher gate potential, but for the case of USUBB/SUB (U₁ = -U₂), the peak height is reduced rapidly, and the width increase as gate potential increases. Because of the periodic magnetic field with zero spatial average in the antiparallel structure, we found that the minimum conductivity decreases with increasing magnetic energy. They show suppression of Klein tunneling which occurs in the zero-conductance plateaus and leads to the robust magnetoresistance plateau and large positive magnetoresistance appears below magnetic energy. For the case of USUBA/SUB and ESUBF/SUB more than magnetic energy, we found that the quasi-linear magnetoresistance feature is applied by an electric field instead of the usual magnetically driven magnetoresistance.