Manipulating electron spin in graphene may enable ambient-temperature FETs

Researchers at Chalmers University, affiliated with the Graphene Flagship, have devised a graphene-based spin field-effect transistor with the ability to function at room temperature. The team used the spin of electrons in graphene and similar layered material heterostructures to fabricate working devices in a step towards combining memory devices and the logic of spintronics.

Graphene spintronics FETs image

The researchers demonstrated that the spin characteristics of graphene can be electrically regulated in a controlled way, even at an ambient temperature. In addition to possibly unlocking various probabilities in spin logic operations, this study also enables integration with magnetic memory elements in a device unit. If further advancements can assist in the production of a spin current without the need for charge flow, the amount of power needed will be considerably reduced, resulting in highly versatile devices.

Read the full story Posted: Jul 09,2017

Manipulating the electron spin can lower the contact resistance in graphene-metal interfaces

NUS researchers discovered that manipulating the electron spin lowers the contact resistance in graphene-metal interfaces, which normally suffer from large electrical resistance.

Spin filtering in metal-graphene interfaces image

The researchers have shown that edga-contacted device geometries in metallic-graphene interfaces feature some of the lowest contact resistances reported to date - significantly lower than in surface-contracted interfaces. The researchers explain that this is due to the different behavior of electron spins in these geometries.

Read the full story Posted: May 22,2017

Zigzag graphene ribbons found to be attractive for spintronics applications

Researchers from Grenoble Alpes University in France have demonstrated (using atomistic calculations) that a lateral electric field can be used to tune the carrier mobility and change the spin polarization of the current driving through zigzag graphene ribbons.

The calculations predict a high variation of the carrier mobility, mean free path and spin polarization in the ZGNRs. It turns out that configurations with almost 100% spin-polarized current can be switched on and off. The researchers say that these effects can be nicely exploited in spintronics devices.

Read the full story Posted: Nov 16,2016

Penn State team controls momentum of electrons in graphene to advance valleytonics, a next-gen technology

Researchers at Pennsylvania State University have developed a device made of bilayer graphene, which provides experimental proof of the ability to control the momentum of electrons. The study is considered as a step forward in a new field of physics called valleytronics.

The team explains that current silicon-based transistor devices rely on the charge of electrons to turn the device on or off, but valleytronics looks into a new way to manipulate electrons based on other variables, called degrees of freedom. Charge is one degree of freedom. Electron spin is another, and the ability to build transistors based on spin, called spintronics, is still in the development stage. A third electronic degree of freedom is the valley state of electrons, which is based on their energy in relation to their momentum.

Read the full story Posted: Oct 12,2016

Saint Jean Carbon achieves magnetoresistance graphene

Saint Jean Carbon, a carbon science company engaged in the exploration of natural graphite properties and related carbon products, has teamed up with the University of Western Ontario to create graphene that has a magnetic field (Magnetoresistance).

One of the involved researchers explained that: "Magnetoresistance (MR) refers to the significant change of electrical resistance of materials under a magnetic field. Magnetoresistance effects have been applied in magnetic sensors, spintronic devices and data storage. Magnetic sensors are extremely useful for today's industry for measurement and control purposes... This happens by detecting changes in electrical resistance brought on by the presence of a magnetic field. This is also known as magnetoresistance (MR). The market size of the magnetic sensor is increasing with annual growth rate at 10% because of new nanomaterials..."

Read the full story Posted: Sep 25,2016

New method yields graphene nanoribbons with zigzag edges

A team of researchers from China and Japan has designed a new method to make minuscule ribbons of graphene that are highly sought-after building blocks for semiconductor devices thanks to their predicted electronic properties. These structures, however, have proven challenging to make.

Previous attempts at making graphene nanoribbons relied on placing sheets of graphene over a layer of silica and using atomic hydrogen to etch strips with zigzag edges, a process known as anisotropic etching. This method, however, only worked well to make ribbons that had two or more graphene layers. Irregularities in silica created by electronic peaks and valleys roughen its surface, so creating precise zigzag edges on graphene monolayers was a challenge.

Read the full story Posted: Aug 02,2016

NRL designs low-defect method to nitrogen dope graphene resulting in tunable bandstructure

A team of scientists at the U.S. Naval Research Laboratory (NRL) has demonstrated hyperthermal ion implantation (HyTII) as an effective means of doping graphene with nitrogen atoms. The result is a low-defect film with a tunable bandstructure that could be useful in a variety of device platforms and applications.

According to the research, the HyTII method delivers a high degree of control including doping concentration and, for the first time, demonstrates depth control of implantation by doping a single monolayer of graphene in a bilayer graphene stack. This further demonstrates that the resulting films have high-quality electronic transport properties that can be described solely by changes in bandstructure rather than the defect-dominated behavior of graphene films doped or functionalized using other methods.

Read the full story Posted: Jun 07,2016

The Graphene Flagship funds five graphene spintronics projects

The Graphene Flagship includes a Spintronics Work Package - the aims to explore graphene's role in spintronics. Last week the participants in this initiative met for the first time in an event organised by the Deputy Leader of the Spintronics Work Package, and hopefully these interesting projects will bear fruit soon.

There are currently five projects in the spintronics field under the flagship:
  • HiMagGraphene: Atomic-scale control of graphene magnetism using hydrogen atoms
  • iSpinText: Induced Spin Textures in van der Waals Heterostructures
  • SOgraph: Tailoring Spin-Orbit effects in Graphene for spin-orbitronic applications
  • TAILSPIN: Tailoring spin-interactions in graphene nanoribbons for ballistic fully spin-polarized devices
  • Trans2DTMD: Theoretical investigation of electronic transport in functionalized 2D transition metal dichalcogenides

Read the full story Posted: Jun 06,2016

Hydrogen atoms magnetize graphene

Researchers at the Autonomous University of Madrid, in collaboration with CIC nanoGUNE and the Institut Néel of Grenoble, have demonstrated that the simple absorption of a hydrogen atom on a layer of graphene magnetizes a large region of it. As a result, by selectively manipulating these hydrogen atoms, it is possible to produce magnetic graphene with atomic precision.

Graphene inherently lacks magnetic properties. The hydrogen atom has the smallest magnetic moment (the magnitude that determines how much and in what direction a magnet will exert force). This work reveals how when a hydrogen atom touches a graphene layer it transfers its magnetic moment to it. The researchers explain that in contraposition to more common magnetic materials such as iron, nickel or cobalt, in which the magnetic moment generated by each atom is located within a few tenths of a nanometre, the magnetic moment induced in the graphene by each atom of hydrogen extends several nanometres, and likewise displays a modulation on an atomic scale.

Read the full story Posted: Apr 29,2016

GNRs with perfect zigzag edges produced from molecules for possible use in spintronics

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.

Read the full story Posted: Mar 27,2016