Tunneling magnetoresistance phenomenon utilizing graphene magnet electrode

Using magnetic rare-metals for spintronic devices is facing serious problems for the environmental contamination and the limited material-resource. In contrast, by fabricating ferromagnetic graphene nanopore arrays (FGNPAs) consisting of honeycomb-like array of hexagonal nanopores with hydrogen-terminated zigzag-type atomic structure edges, we reported observation of polarized electron spins spontaneously driven from the pore edge states, resulting in rare-metal-free flatenergy- band ferromagnetism.

Here, we demonstrate observation of tunneling magnetoresistance (TMR) behaviors on the junction of cobalt/SiO2/FGNPA electrode, serving as a prototype structure for future rare-metal free TMR devices using magnetic graphene electrodes. Gradual change in TMR ratios is observed across zero-magnetic field, arising from specified alignment between pore-edge- and cobalt-spins.

The TMR ratios can be controlled by applying back-gate voltage and by modulating interpore distance. Annealing the SiO2/FGNPA junction also drastically enhances TMR ratios up to similar to 100%. (C) 2014 AIP Publishing LLC.