Four years of world-leading research
It’s been four years since the National Graphene Institute (NGI) at The University of Manchester officially opened its doors. Since then it has welcomed visitors from across the globe including the Duke and Duchess of Cambridge and President Xi Jingping of the People’s Republic of China. It has also been at the forefront of graphene product development from light bulbs, running shoes, water bottles and even watches.
However, bricks and mortar can only take you so far. The true heart of the NGI is the expertise and knowledge of the people that are working within its walls.
The first graphene paper: Electric Field effect in Atomically Thin Carbon Films was named by Nature as one of the 100 most cited research papers in science history.
The University of Manchester is known as the ‘home of graphene’. Since the initial isolation the 300 strong graphene community has pushed the boundaries to remain a forerunner in graphene and 2D materials research.
To date 453 papers have been published from the National Graphene Institute with a large portion of them in the world’s most respectable journals. Researchers from the NGI and the School of Physics and Astronomy have had four papers published in Science and Nature just within the first two months of 2019. This is unprecedented for any world-class institute entering into only its fourth full year of operation. Here are just some of the latest highlights published in 2019.
The team led by Dr Artem Mishchenko, Prof Vladimir Fal’ko and Prof Sir Andre Geim, discovered the quantum Hall effect (QHE) in bulk graphite – a layered crystal consisting of stacked graphene layers. This is an unexpected result because the quantum Hall effect is possible only in two-dimensional materials where the movement of electrons’ motion is restricted. They have also found that the material behaves differently depending on whether it contains odd or even number of graphene layers – even when the number of layers in the crystal exceeds hundreds. The work is an important step to the understanding of the fundamental properties of graphite, which have often been misunderstood.
14 years since the isolation, graphene is still throwing up unexpected phenomena. A team lead by Prof Andre Geim and Dr Denis Bandurin has discovered that electrons in graphene act like a very unique liquid.
The movement of electron fluid in graphene has, for the first time, been observed to exist with two separate viscosities showing that the Hall effect – a phenomenon well known for more than a century – is no longer as universal as it was thought to be.
The classical Hall effect is no longer as universal as it was thought to be, in a research paper published in Science found that the Hall effect can even be significantly altered in graphene. The phenomenon was observed at room temperature – something that will have important implications for when making electronic devices from graphene.
But its not only 2D material graphene that researchers have been observing- they have begun to look at other materials and their 2D counterparts.
Hexagonal Boron Nitride, tungsten disulphide, molybdenum disulphide are just some of the tongue twister materials which have allowed scientists to layer these materials, similar to stacking bricks of Lego in a precisely chosen sequence known as van der Waals heterostructures to create high-performance structures tailored to a specific purpose.
As published in Nature, researchers from the Micromegas team at the Physics Department at ENS, Paris in collaboration with the NGI, have been able to highlight mechano-sensitive properties of ion transport in few angstroms thick artificial channels.
Similar to our computers which handle electrons to perform the calculations and logics, all the circuitry in living beings is based on the transport of ions, such as sodium, chloride and calcium. Nature exploits incredibly subtle transport of these elementary charges and an artillery of ion channels to perform advanced functions by manipulating the – often exotic – behaviour of ion transport at molecular scales. Achieving such features in artificial channels remains a considerable challenge.
Just over two years ago, Manchester researchers led by Dr Radha Boya and Prof Andre Geim showed that by stacking two-dimensional atomic layers similar to stacking bricks of Lego, it is indeed possible to assemble molecular and smooth channels at the atomic scale in a controlled manner. The atomic layers used for building the channel are held together by so-called van der Waals forces. Using these channels, the new experiments show that considerable ionic current can be generated when a flow is induced by applying a pressure difference. Separating two miniature baths of salt solutions, these angstrom scale channels generate ionic current when water molecules are mechanically pushed through them.
In years to come, we won’t be restricted by the materials that already exist. Combining graphene with other materials, which individually have excellent characteristics complimentary to the extraordinary properties of graphene, and has resulted in exciting scientific developments and could produce applications as yet beyond our imagination.
In the ground-breaking study published in Nature, scientists have also found that the properties of the new hybrid material can be precisely controlled by twisting two stacked atomic layers, opening the way for the unique design of new materials and electronic devices for future technologies.
The new structures open a huge potential to create numerous designer-materials and novel devices by stacking together any number of atomically thin layers. Hundreds of combinations become possible otherwise inaccessible in traditional three-dimensional materials, potentially giving access to new unexplored optoelectronic device functionality or unusual material properties.
Graphene was the world’s first two-dimensional material, its range of superlative properties: fantastic strength, conductivity, flexibility, transparency, has paved the way for applications ranging from water filtration, bendable smartphones and rust proof coatings to anti-cancer drug delivery systems.
This material never ceases to amaze, and teams across the University continue to take a concerted and creative approach to tackling the scientific unknowns of these materials.