Spintronics - Page 5

Researchers from Empa, the Max Planck Institute in Mainz and the Technical University of Dresden have succeeded, for the first time, in producing graphene nanoribbons (GNRs) with perfect zigzag edges from molecules. Electrons on these zigzag edges exhibit different (and coupled) rotational directions (referred to as "spin"). This could make GNRs highly attractive for next-gen electronics, namely spintronics.

In their work, the research team describes how it managed to synthesize GNRs with perfectly zigzagged edges using suitable carbon precursor molecules and a perfected manufacturing process. The zigzags followed a very specific geometry along the longitudinal axis of the ribbons. This is an important step, because researchers can thus give graphene ribbons different properties via the geometry of the ribbons and especially via the structure of their edges.

Scientists at Cornell University have developed a chiral thin film through rotational stacking of graphene sheets, the first such exploration of chirality at the nano scale. This material may be of interest in the fields of polarization optics, stereochemistry, optoelectronics and spintronics.

For the experiment,the researchers grew graphene sheets on copper, then cut them into multiple sheets. Those sheets were then stacked, with each sheet rotated slightly before being placed on the one below it. The rotation went clockwise on one stack and counter-clockwise on the other to form right-handed and left-handed stacks. Circularly polarized light alternating left-handed and right-handed beams were shone onto the stacks, and circular dichroism (or CD, the differential absorption of left- and right-handed light), was measured.

Researchers at Joseph Fourier University in Grenoble, France, have found that coating a cobalt film in graphene could double the film's perpendicular magnetic anisotropy (PMA), so that it reaches a value 20 times higher than that of traditional metallic cobalt/platinum multilayers that are being researched for this property. In a material with a high PMA, the magnetization is oriented perpendicular to the interface of the material's layers. High-PMA materials are being researched for their applications in next-generation spintronic devices, such as high-density memories and heat-tolerant logic gates. 

A major goal in developing spintronic devices is to reduce the size of the devices while achieving long-term information retention of 10-plus years. In order to do this, the storage material must have a large PMA. Enhancement of effective PMA could be achieved either by increasing the surface PMA or by minimizing the saturation magnetization of the storage layer. These co-graphene heterostructures benefit from both these properties. The PMA enhancement in the graphene-coated cobalt films originates at the atomic level, where graphene affects the energy of cobalt's different electron orbitals. The graphene coating changes how these orbitals overlap with one another, which in turn changes the direction of the cobalt film's overall magnetic field: some of the magnetization that was originally parallel to the film surface is now oriented perpendicular to the film surface.

Scientists at the U.S. Naval Research Laboratory (NRL) have created a new type of room-temperature tunnel device structure in which the tunnel barrier and transport channel are both made of graphene. Such functionalized homoepitaxial structures can be seen as an elegant approach for realization of graphene-based spintronic devices.

The scientists show that hydrogenated graphene acts as a tunnel barrier on another layer of graphene for charge and spin transport. They demonstrate spin-polarized tunnel injection through the hydrogenated graphene, and lateral transport, precession and electrical detection of pure spin current in the graphene channel. The team further reports higher spin polarization values than found using more common oxide tunnel barriers, and spin transport at room temperature.

A science and technology roadmap for graphene, related two-dimensional crystals, other 2d materials, and hybrid systems was put together in a joint effort by over 60 academics and industrialists. The roadmap covers the next 10 years and beyond, and its objective is to guide the research community and industry toward the development of products based on graphene and related materials.

The roadmap highlights three broad areas of activity. The first task is to identify new layered materials, assess their potential, and develop reliable, reproducible and safe means of producing them on an industrial scale. Identification of new device concepts enabled by 2d materials is also required, along with the development of component technologies. The ultimate goal is to integrate components and structures based on 2d materials into systems capable of providing new functionalities and application areas.

The Graphene Flagship announced a work package that explores the potential of graphene spintronics for future devices and applications. It is searching for a new partner company to support device development and commercialisation of graphene spintronics, by applying it in specific device architectures dedicated to commercially viable applications and determining the required figures of merits. This can include devices which require optimised (long distance) spin transport, spin-based sensors, and new integrated two-dimensional spin valve architectures.

The Graphene Flagship expects that at the start of the Horizon 2020 phase (April 2016), spin injection and spin transport in graphene and related materials will have been characterised and the resulting functional properties will have been understood and modelled. 

Researchers at the University of California at Riverside found a way to introduce magnetism in graphene while still preserving electronics properties. This may represent a significant step forward in the use of graphene in chips and electronics, since doping in the past induced magnetism but damaged graphene's electronic properties. this method can also be used in spintronics - chips that use electronic spin to store data.

The scientists explain they have overcome the problem by moving a graphene sheet very close to an electrical insulator with magnetic properties, since placing graphene on an insulating magnetic substrate can make the material ferromagnetic without disturbing its conductivity. The magnetic graphene is said to acquire new electronic properties, and so new quantum phenomena can take place.

Spanish researchers discovered a way of using lead atoms and graphene to create a powerful magnetic field by the interaction of the electrons' spin with their orbital movement. The scientists believe that this discovery could come in handy for spintronics applications. 

The researchers from IMDEA Nanoscience, the Autonomous University of Madrid, the Madrid Institute of Materials Science (CSIC) and the University of the Basque Country say that the key to their discovery was intercalation of atoms or Pb islands below the hexagons of carbon that make up graphene. This brings about a significant interaction between two electron characteristics - their spin and their orbit.

QuantumWise released a new version of their Atomistix ToolKit (ATK) simulation software. The new version speeds up simulation performance by 40%. Besides the performance boost, the new ATK 2014 release includes several new features such as Spin-orbit interaction and Meta-GGA for accurate first-principle prediction of the electronic structure. These features can be used for both bulk semiconductor materials and nanostructures and 2D materials like graphene.

The inclusion of noncollinear spin enables computations of spin transfer torque and other properties of magnetic tunnel junctions - useful for MRAM devices and other Spintronics applications.

The Spanish ICN2 Theoretical and Computational Nanoscience Group declare a unique graphene mechanism especially suited for spintronics applications.

Graphene's small intrinsic spin-orbit coupling and vanishing hyperfine interaction is known as holding great potential for use in spintronics applications, and this unprcedented spin relaxation mechanism for non-magnetic samples can prove to be a major step towards utilizing graphene's properties in non-charge-based information procesing and computing (a new generation of active- CMOS compatible- spintronic devices together with a non-voltaic low energy MRAM memories).