Spin valve effect of NiFe/graphene/NiFe junctions
When spins are injected through graphene layers from a transition metal ferromagnet, high spin polarization can be achieved. When detected by another ferromagnet, the spin-polarized current makes high- and low-resistance states in a ferromagnet/graphene/ferromagnet junction. Here, we report manifest spin valve effects from room temperature to 10 K in junctions comprising NiFe electrodes and an interlayer made of double-layer or single-layer graphene grown by chemical vapor deposition. We have found that the spin valve effect is stronger with double-layer graphene than with single-layer graphene. The ratio of relative magnetoresistance increases from 0.09% at room temperature to 0.14% at 10 K for single-layer graphene and from 0.27% at room temperature to 0.48% at 10 K for double-layer graphene. The spin valve effect is perceived to retain the spin-polarized transport in the vertical direction and the hysteretic nature of magnetoresistance provides the basic functionality of a memory device. We have also found that the junction resistance decreases monotonically as temperature is lowered and the current-voltage characteristics show linear behaviour. These results revealed that a graphene interlayer works not as a tunnel barrier but rather as a conducting thin film between two NiFe electrodes.
Keywordsgraphene spin valve magnetic junction magnetoresistance spintronics
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- Karpan, V. M.; Khomyakov, P. A.; Starikov, A. A.; Giovannetti, G.; Zwierzycki, M.; Talanana, M.; Brocks, G.; van den Brink, J.; Kelly, P. J. Theoretical prediction of perfect spin filtering at interfaces between close-packed surfaces of Ni or Co and graphite or graphene. Phys. Rev. B 2008, 78, 195419.CrossRefGoogle Scholar
- Das, A.; Pisana, S.; Chakraborty, B.; Piscanec, S.; Saha, S. K.; Waghmare, U. V.; Novoselov, K. S.; Krishnamurthy, H. R.; Geim, A. K.; Ferrari, A. C. et al. Monitoring dopants by Raman scattering in an electrochemically top-gated graphene transistor. Nat. Nanotechnol. 2008, 3, 210–215.CrossRefGoogle Scholar
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