Spintronics - Page 6

Researchers from UCLA and Tohoku University developed a new self-assembly method to fabricate pristine graphene nanoribbons with zigzag edges. Those ribbons are especially suited for spintronics applications, as zigzag edged graphene is most magnetic.

The new technique use a copper substrate that was altered so that carbon molecules automatically assemble on it as zigzag ribbons. The researchers can control the ribbons length, edge configuration and location on the substrate.

Researchers from the US Naval Research Laboratory (NRL) developed a new type of tunnel device structure in which both the tunnel barrier and transport channel are made from graphene. The researchers say that this device features the highest spin injection values yet measured for graphene, and this design could pave they way towards highly functional and scalable graphene electronic and spintronic devices.

The tunnel barrier is made from dilutely fluorinated graphene while the charge and transport layer is made from graphene. The researcher demonstrated tunnel injection through the fluorinated graphene, and lateral transport and electrical detection of pure spin current in the graphene channel.

Researchers from MIT discovered that under a powerful magnetic field and at very low temperatures, graphene can filter electrons according to the direction of their spin. This is something that cannot be done by any conventional electronic system - and may make graphene very useful for quantum computing.

It is known that when a magnetic field is turned on perpendicular to a graphene flake, current flows only along the edge, and in one direction (clockwise or counterclockwise, depending on the magnetic field orientation), while the bulk graphene sheet remains insulating. This is called the Quantum Hall effect.

Researchers from the US, Singapore, Brazil and Ireland have theoretically shown that if you fold a graphene sheet in a fin-like structure and expose it to a magnetic field you open up a bandgap. This will also produce spin-polarized current, which should make it useful in Spintronics applications.

The researchers say that this folding can be easily achieved by depositing graphene on a substrate with periodic trenches.

Researchers from UC Berkeley, Florida International University (FIU) and the Georgia Institute of Technology demonstrated for the first time the presence of magnetic properties in graphene nanostructures at room temperature. Magnetic graphene could have potential applications in information processing, medicine and Spintronics. 

To achieve this they functionalized the graphene with nitrophenyl. The researchers thus confirmed the presence of magnetic order in nanoparticle-functionalized graphene. The graphene was epitaxially grown at Georgia Tech, chemically functionalized at UC Riverside and studied at FIU and UC Berkeley.

Researchers from the University of Vienna managed to assemble a new structure of high-quality metal silicides (nickel, cobalt and iron) coated with a graphene sheets. Using angle-resolved photoemission spectroscopy (ARPES), the researchers studied the electronic properties of this new material.

It was found that the graphene protects the silicides against oxidation, while barely interacting with the silicides themselves. The unique properties of the graphene are widely preserved. This means that this new composite material is a good way to incorporate graphene with existing metal silicide technology, which will hopefully enable the usage of graphene in applications such as semiconductor devices, spintronics, photovoltaics and thermoelectrics.

Researcher from Japan's Advanced Science Research Center, the Atomic Energy Agency and the National Institute for Materials Science developed a way to detect the electronic spin state of graphene contacted to a magnetic metal, using a spin-polarized metastable helium beam.

Detecting the spin state of graphene is difficult because of the weak signal from the graphene compared to the strong signal of the magnetic substrate it sits on, and this new achievement is important if graphene is to be used as a Spintronics material.

Graphene Nanoribbons have two kinds of edges: zigzag or "armchair". Edge magnetism in zigzag graphene nanoribbons (zGNRs) has been predicted in theory but not in experiments, probably due to the instability of the edges and the usual choice of hydrogen as a terminal to the edges (which can only be stabilized at extremely low hydrogen concentrations). A better terminal is required if we want to preserve the magnetism (which is required for Spintronics application, for example).

Now researchers from Puerto Rico and China have designed new terminals based on ethylene (C₂H₄). They say it's the ideal material to preserve the edge magnetism. This will hopefully indeed enable Spintronics applications based on zGNRs.

Researchers from the University of Manchester managed to create elementary magnetic moments in graphene and then switch them on and off. This is the first time magnetism itself has been toggled, rather than the magnetization direction being reversed. They say this is a major breakthrough on the way towards graphene based Spintronics transistor-like devices.

The new research shows that electrons in graphene condense around vacancies ("holes" in the graphene sheet created when some carbon atoms are removed) - and create small "electronic cloud". These clouds carry a spin, and the researchers managed to dissipate and then condense back those clouds.

Researchers from Spain have succeeded in giving graphene magnetic properties - they have basically managed to create a hybrid graphene surface that behaves like a magnet. This may enable graphene-based Spintronic devices.

A magnetic material is a material in which most electrons have the same spin. In order to achieve that, the researchers grew a graphene sheet on a ruthernium single crystal substrate. Then they evaporated TCNQ (tetracyano-p-quinodimethane, which acts as a semiconductor at very low temperatures) molecules on the graphene surface. The TCNQ molecule acquired long-range magnetic order.