Graphene-based structures found to have extremely long spin relaxation lifetime

Nov 18, 2017

Researchers from Spain's ICN2 institute have discovered that graphene/TMDC heterostructures can exhibit etremely long spin relaxation lifetime. These structure feature lifetimes that are orders of magnitude larger than anything observed in 2D materials - and in fact these results point to a qualitatively new regime of spin relaxation.

Graphene on TMDC image (ICN2)

Spin relaxation lifetime means that time it takes for the spin of electrons in a spin current to lose their spin (return to the natural random disordered state). A long lifetime is very important for spintronics devices. This new study reveals that the rate at which spins relax in graphene/TMDC systems depends strongly on whether they are pointing in or out of the graphene plane, with out-of-plane spins lasting tens or hundreds of times longer than in-plane spins.

Manchester team creates graphene oxide membranes that can filter organic solvents

Nov 15, 2017

Researchers at the National Graphene Institute and School of Chemical Engineering and Analytical Science at The University of Manchester have developed an ultra-thin membrane using graphene-oxide sheets, that were assembled in a way that they were able to completely remove various organic dyes, dissolved in methanol, which were as small as a nanometre. This is exciting as GO membranes were once thought to be permeable only to aqueous solutions, but the researchers developed a new form of graphene oxide membrane that can filter organic solvents.

Manchetser and NGI team created unique GO membranes image

In the newly developed ultrathin membranes, graphene-oxide sheets are assembled in such a way that pinholes formed during the assembly are interconnected by graphene nanochannels, which produces an atomic-scale sieve allowing the large flow of solvents through the membrane. When used to filter Cognac and whisky, the membrane permitted alcohol to pass through but trapped the larger molecules that gives the whisky its color. Professor Nair, which led the group, said that "the clear whisky smells similar to the original whisky but we are not allowed to drink it in the lab, however it was a funny Friday night experiment!”

Low-cost batteries could be made from graphene, waste graphite and scrap metal

Nov 14, 2017

Researchers from Empa and ETH Zürich have used graphene, waste graphite and scrap metal to make low-cost batteries.

The researchers’ ambitious goal at Empa is to make a battery out of the most common elements in the Earth’s crust – such as magnesium or aluminum. These metals offer a high degree of safety, even if the anode is made of pure metal. This also offers the opportunity to assemble the batteries in a very simple and inexpensive way and to rapidly upscale the production. To make such batteries work, the liquid electrolyte needs to consist of special ions that do not crystallize at room temperature. The researchers were looking for a suitable cathode material, and decided to turn the principle of the lithium ion battery upside down.

Graphene-TMDC combination could enable ultra-low power transistors and electrical spin control

Nov 12, 2017

Teams from the University of York and Roma Tre University state that ultra-low-power transistors could be built using composite materials based on single layers of graphene and transition metal dichalcogenides (TMDC). These materials, they note, could be used to achieve a sought-after electrical control over electron spin.

Graphene and TDMCs to enable efficient transistors image

The teams explained “we found this can be achieved with little effort when 2D graphene is paired with certain semiconducting layered materials. Our calculations show that the application of small voltages across the graphene layer induces a net polarization of conduction spins". The team showed that when a small current is passed through the graphene layer, the electrons’ spin polarize in plane due to ‘spin-orbital’ forces brought about by the proximity to the TMDC base. They also showed the efficiency of charge-to-spin conversion can be quite high, even at room temperature.

Researchers at The University of Manchester create miniaturized pressure sensors using graphene membranes

Nov 12, 2017

Researchers at The University of Manchester have fabricated highly sensitive miniaturized pressure sensors using graphene membranes.

The team reported that the new sensor was made possible by developing a way to effectively float a graphene membrane mere nanometers above a silicon chip. When pressure moves this membrane closer to the surface of the chip, the resulting change in capacitance is measured to read out the pressure change. By fabricating thousands of such floating membranes next to each other, a device can be made of exceptionally high sensitivity to pressure changes.