Research Article

Nano Research

, Volume 6, Issue 5, pp 373-380

First online:

Spin valve effect of NiFe/graphene/NiFe junctions

  • Muhammad Zahir IqbalAffiliated withDepartment of Physics and Graphene Research Institute, Sejong University
  • , Muhammad Waqas IqbalAffiliated withDepartment of Physics and Graphene Research Institute, Sejong University
  • , Jae Hong LeeAffiliated withDepartment of Physics and Graphene Research Institute, Sejong University
  • , Yong Seung KimAffiliated withDepartment of Physics and Graphene Research Institute, Sejong University
  • , Seung-Hyun ChunAffiliated withDepartment of Physics and Graphene Research Institute, Sejong University
  • , Jonghwa EomAffiliated withDepartment of Physics and Graphene Research Institute, Sejong University Email author 

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Abstract

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.
https://static-content.springer.com/image/art%3A10.1007%2Fs12274-013-0314-x/MediaObjects/12274_2013_314_Fig1_HTML.gif

Keywords

graphene spin valve magnetic junction magnetoresistance spintronics