Elucidation of spin state of conduction electrons in graphene

Jul 22, 2013
When a low velocity spin-polarized metastable He beam is irradiated on the specimen surface, the He atoms rebound above the surface without penetrating to the interior. As a result, it is possible to selectively detect surface information. During the collision, the 1s-hole (black broken line arrow) is filled by a surface electron and the He atom returns to its ground state by releasing the 2s electron. Since the surface electron filing the 1s-hole should have the same spin to the hole, the ejected electron carries the spin information of surface electrons. By aligning the spin direction of 1s-hole a metastable He becomes a spin detector. In the present study the spin state of topmost layer of graphene/Ni(111), namely graphene, has been selectively detected with this method.

Using a spin-polarized metastable helium beam, a group headed by Dr. Shiro Entani, who is a limited-term researcher at the Advanced Science Research Center, Japan Atomic Energy Agency (President: Shojiro Matsuura) and Dr. Yasushi Yamauchi, a Group Leader in the Nano Characterization Unit, National Institute for Materials Science (President: Sukekatsu Ushioda) 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 utilize in spin devices, techniques for controlling its 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 . 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 , is buried in the strong signal from the magnetic substrate.

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 polarization 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 2-dimensional materials including graphene which are a focus of attention as new materials, as well as device applications such as development of spin injection techniques, etc.

Explore further: How bubble studies benefit science and engineering

Related Stories

Graphene switches: Team makes it to first base

Nov 27, 2012

Ever since graphene was first isolated a few years ago, this quasi-two-dimensional network made up of a single layer of carbon atoms has been considered the magic material. Not only is graphene mechanically ...

New magnetic graphene may revolutionise electronics

May 10, 2013

Researchers from IMDEA-Nanociencia Institute and from Autonoma and Complutense Universities of Madrid (Spain) have managed to give graphene magnetic properties. The breakthrough, published in the journal ...

Controlling magnetic clouds in graphene

Jun 12, 2013

(Phys.org) —Wonder material graphene can be made magnetic and its magnetism switched on and off at the press of a button, opening a new avenue towards electronics with very low energy consumption.

Physicists explore properties of electrons in graphene

Aug 10, 2012

Scientists from Georgia State University and the Georgia Institute of Technology have found a new way to examine certain properties of electrons in graphene – a very thin material that may hold the key to new technologies ...

Recommended for you

New method for non-invasive prostate cancer screening

9 hours ago

Cancer screening is a critical approach for preventing cancer deaths because cases caught early are often more treatable. But while there are already existing ways to screen for different types of cancer, ...

How bubble studies benefit science and engineering

10 hours ago

The image above shows a perfect bubble imploding in weightlessness. This bubble, and many like it, are produced by the researchers from the École Polytechnique Fédérale de Lausanne in Switzerland. What ...

Famous Feynman lectures put online with free access

11 hours ago

(Phys.org) —Back in the early sixties, physicist Richard Feynman gave a series of lectures on physics to first year students at Caltech—those lectures were subsequently put into print and made into text ...

Single laser stops molecular tumbling motion instantly

15 hours ago

In the quantum world, making the simple atom behave is one thing, but making the more complex molecule behave is another story. Now Northwestern University scientists have figured out an elegant way to stop a molecule from ...

User comments : 0