2D materials - Page 2

The Australian Research Council (ARC) has announced the launch of the ARC Research Hub for advanced manufacturing with 2D Materials. The hub aims to develop the application of 2D materials for water treatment, batteries, functional paints and coatings and other key areas of economic and technological interest.

“The ARC proudly supports research excellence that positively impacts everyday Australians and this is evident in the establishment of the ARC Research Hub for advanced manufacturing with 2D Materials,” said Dr. Richard Johnson, deputy chief executive officer, ARC. “Among the research outcomes expected to emerge from the hub will be high-powered, low-cost graphene-based supercapacitors, capable of storing energy for use in electric vehicles, as well as improvements in the supply chain of materials used in the manufacturing of these devices, allowing industry to thrive,” continued Dr. Johnson.

Researchers at Spain's IMDEA Nanoscience, Donostia International Physics Center, Ikerbasque and Poland's University of Opole have developed an analytical method to explain the formation of a quasi-perfect 1D moiré pattern in twisted bilayer graphene. The pattern, naturally occurring in piled 2D materials when a strain force is applied, represents a set of channels for electrons.

The team studied the effects of strain in moiré systems composed of honeycomb lattices. The scientists elucidated the formation of almost perfect one-dimensional moiré patterns in twisted bilayer systems. The formation of such patterns is a consequence of an interplay between twist and strain which gives rise to a collapse of the reciprocal space unit cell. As a criterion for such collapse, they found a simple relation between the two quantities and the material specific Poisson ratio. The induced one-dimensional behavior is characterized by two, usually incommensurate, periodicities.

It was reported that China aims to accelerate the industrialization of materials like graphene and liquid metals, and so the Ministry of Industry and Information Technology and State-owned Assets Supervision and Administration Commission jointly released a list of important new materials that they will focus on advancing.

These materials represent the direction and trend of the development of the new material industry, which is an important entry point for building new growth engines, the ministries said. For instance, the ministries called for their subordinate bodies to encourage enterprises to advance the industrialization of graphene in potential sectors such as rail traffic, aerospace equipment, new energy and new-generation information technologies.

Researchers from Columbia University, Technical University of Denmark, Aarhus University, Université Paris-Saclay and Japan's National Institute for Materials Science have designed a simple fabrication technique that could help study the fundamental properties of twisted layers of graphene and other 2D materials in a more systematic and reproducible way. The team used long “ribbons” of graphene, rather than square flakes, to create devices that offer a new level of predictability and control over both twist angle and strain.

Graphene devices have typically been assembled from atom-thin flakes of graphene that are just a few square millimeters. The resulting twist angle between the sheets is fixed in place, and the flakes can be tricky to layer together smoothly. “Imagine graphene as pieces of saran wrap—when you put two pieces together you get random little wrinkles and bubbles,” says Columbia postdoc Bjarke Jessen, a co-author on the paper. Those bubbles and wrinkles are akin to changes in the twist angle between the sheets and the physical strain that develops in between and can cause the material to buckle, bend, and pinch randomly. All these variations can yield new behaviors, but they have been difficult to control within and between devices.

Researchers from the University of Washington and Japan's National Institute for Materials Science have performed transport measurements of dual-gated devices constructed by slightly rotating a monolayer graphene sheet atop a thin bulk graphite crystal. They surprisingly found that it is possible to imbue graphite with physical properties similar to graphene. 

Not only was this result unexpected, the team also believes its approach could be used to test whether similar types of bulk materials can also take on 2D-like properties.  

Graphene and graphene-like materials can host—at their edges—localized states whose properties can differ dramatically from those of bulk states. Three types of edge states have been established in these materials—zigzag, bearded, and armchair—named after their geometry. Now, researchers from Nankai University and Shanxi University used a graphene-like photonic crystal to demonstrate the possibility of a fourth edge, called twig, with exotic topological features. Their results may broaden the understanding of graphene edge states, as well as open new avenues for realization of robust edge localization and nontrivial topological phases based on Dirac-like materials.

The team explained that the main findings were that the twig edge is a generic type of honeycomb lattice (HCL) edge complementary to the armchair edge, formed by choosing the right primitive cell (rather than simple lattice cutting or Klein edge modification). In addition, the twig edge states form a complete flat band across the Brillouin zone with zero-energy degeneracy, characterized by nontrivial topological winding of the lattice Hamiltonian. The twig edge states can also be elongated or compactly localized at the boundary, manifesting both flat band and topological features. 

Earlier this year, Tohoku University researchers created a technique that could micro/nanofabricate silicon nitride thin devices with thicknesses ranging from 5 to 50 nanometers. The method employed a femtosecond laser, which emitted extremely short, rapid pulses of light. It turned out to be capable of quickly and conveniently processing thin materials without a vacuum environment.

By applying this method to an ultra-thin atomic layer of graphene, the same group has now succeeded in performing a multi-point hole drilling without damaging the graphene film. 

A research team at Chalmers University of Technology, Lund University and Uppsala University in Sweden have managed to create a device made of a two-dimensional magnetic quantum material that can work in room temperature. Quantum materials with magnetic properties are believed to pave the way for ultra-fast and considerably more energy efficient computers and mobile devices, but until now, these types of materials tended to only work in extremely cold temperatures. 

The group of researchers has been able to demonstrate, for the very first time, a new two-dimensional magnetic material-based device at room temperature. They used an iron-based alloy (Fe₅GeTe₂) with graphene which can be used as a source and detector for spin polarized electrons. The breakthrough is believed to enable a range of technical applications in several industries as well as in our everyday lives.

Researchers from the University of Amsterdam, New York University and Spain's CSIC have developed a way to build micrometer-size models of atomic graphene using 'patchy particles’ - particles which are large enough to be easily visible in a microscope but small enough to reproduce many of the properties of actual atoms, can interact with the same coordination as the atoms in graphene, and form the same structures.

Using these patchy particles, the team built a model system and used it to obtain insight into the defects in 2D materials, including their formation and evolution over time. 

Researchers from California Institute of Technology (Caltech) and Japan's National Institute for Materials Science have shown that when tungsten diselenide is added to graphene, graphene's electrical properties can be enhanced.

When two or more graphene sheets are stacked on top of each other, the resulting material can exhibit vastly different electronic properties depending on the alignment of those sheets in relation to one another. For instance, when the second sheet of graphene is "twisted" by just 1.05 degrees (a value known as the "magic angle") in relation to the sheet it is laid on top of, the resulting stack can be either a superconductor that conducts electricity with absolutely no resistance whatsoever or an insulator that completely blocks the passage of electricity. Research conducted in 2022 shows that even untwisted graphene bilayers can exhibit superconductivity. Untwisted bilayers of graphene are easier to fabricate in bulk than their twisted counterparts, but the superconductive state in these untwisted bilayers is more delicate, harder to tune, and only occurs at temperatures that are about a hundred times lower than in twisted structures (such temperatures typically can only be achieved through the use of liquid helium). The recent research shows a way to significantly improve upon this fragile superconductivity with tungsten diselenide.