Researchers detect electronic spin state of graphene
A team of researchers in Japan has released the details of their research centred around the spin properties and various device applications of graphene and other 2D materials. Using a spin-polarized metastable helium beam, the group headed by Shiro Entani, a limited-term researcher at the Advanced Science Research Centre, Japan Atomic Energy Agency, and Yasushi Yamauchi, a group leader in the nano characterisation unit, National Institute for Materials Science succeeded in detecting the electronic spin state of only the graphene contacted to a magnetic metal in devices.
Graphene is considered a promising substrate material for next-generation spintronics, as it possesses many properties that are suitable for transmission of electronic spin information. In order to utilise graphene in spin devices, techniques for controlling its spin state are indispensable, and among these, the development of a spin injection technique using a magnetic electrode is a key issue. In developing these techniques, first, it is necessary to know the spin state of the graphene which is contacted to the magnetic metal electrode. It was difficult, however, for conventional techniques to selectively obtain the spin information of the graphene because the weak signal from the graphene, which comprises a single atomic layer, is buried in the strong signal from the magnetic substrate.
Figure 1: The spin state of topmost layer of graphene/Ni(111) has been selectively detected with this method.
In this study, the JAEA-NIMS research group succeeded for the first time in observing the electronic spin state of only the graphene by measuring a junction of graphene and magnetic metal (nickel) with a spin-polarized metastable helium (He) beam. The results revealed that, in conduction electrons of graphene contacted to nickel, spin polarisation occurs with the same orientation as the spin of the nickel.
This research achievement is expected to greatly advance research on the spin properties of various 2D materials including graphene, which are a focus of attention as new spintronics materials, as well as device applications such as development of spin injection techniques, etc.