MIT News July 8, 2022 Despite multitudes of correlated phases observed in moiré systems, robust superconductivity appears the least common, found only in magic-angle twisted bilayer graphene (MATBG) and more recently in magic-angle twisted trilayer graphene. An international team of researchers (USA – MIT, Japan) has reported experimental realization of superconducting magic-angle twisted four-layer and five-layer graphene, hence establishing alternating twist magic-angle multilayer graphene as a robust family of moiré superconductors. This finding suggests that the flat bands shared by the members play a central role in the superconductivity. Their measurements in parallel magnetic fields reveal a clear distinction between […]
Tag Archives: Graphene
New member added to carbon material family, a two-dimensional monolayer polymeric fullerene
Phys.org June 15, 2022 It is a challenge to prepare large-sized single-crystal 2D carbon materials with moderate bandgaps to complement zero-bandgap graphene. Researchers in Chia prepared a single-crystal 2D carbon material, namely monolayer quasi-hexagonal-phase fullerene (C60) via an interlayer bonding cleavage strategy. In this monolayer polymeric C60, cluster cages of C60 are covalently bonded with each other in a plane, forming a regular topology that is distinct from that in conventional 2D materials. It exhibited high crystallinity and good thermodynamic stability, and the electronic band structure measurement revealed a transport bandgap of about 1.6 electronvolts. An asymmetric lattice structure endows monolayer […]
Long-hypothesized ‘next generation wonder material’ created
Science Daily May 21, 2022 Scientists have long been interested in the construction of new or novel carbon allotropes. The most well-known carbon allotropes are graphite and diamonds, which are created out of sp2 carbon and sp3 carbon, respectively. However, the traditional methods don’t allow for the different types of carbon to be synthesized together in large capacity. Researchers at the University of Colorado used alkyne metathesis as well as thermodynamics and kinetic control to successfully create a material that could rival the conductivity of graphene but with control. Now the team is looking into the details of it, including […]
Synthesis of two-dimensional holey graphyne
Science Daily May 18, 2022 While it is possible to overcome limitations of graphene by doping or functionalizing there is also much interest in the search for new types of 2D carbon allotropes. Recently researchers found a top-down way to produce graphene oxides by creating many holes in its structure. An international team of researchers (South Korea, USA – University of Puerto Rico) has developed a bottom-up approach for creating “holey-graphyne” (HGY) constructing the topologically 2D carbon material atom by atom. It consists of alternately HYG linked between benzene rings and C≡C bonds, composed of a pattern of six-vertex and […]
Light derails electrons through graphene (w/video)
Nanowerk March 24, 2022 An international team of researchers (Spain, USA – Columbia University, Japan, Singapore) showed that by applying circular polarized infrared light onto the bilayer graphene device, they could selectively excite one specific valley population of electrons in the material, which generated a photovoltage perpendicular to the usual electron flow. By engineering the device and setup in such a way that current only flows with light illumination, they were able to avoid the background noise that hampers measurements and achieved a sensitivity in the detection several orders of magnitude better than any other 2D material. They could control […]
Graphene spintronics: 1D contacts improve mobility in nano-scale devices
Science Daily February 11, 2022 An international team of researchers (UK, Japan) used monolayer graphene encapsulated by hexagonal boron nitride in van der Waals heterostructure with one-dimensional contacts. They measured electron mobility up to 130,000cm2/Vs at low temperatures (20K or -253oC) and spin diffusion lengths approaching 20 μm. The nanoscale-wide 1D contacts allow spin injection both at room and at low temperature, with the latter exhibiting efficiency comparable with 2D tunnel contacts. At low temperature, the spin signals can be enhanced by as much as an order of magnitude by electrostatic gating, adding new functionality. According to the researchers the […]
Laser scribed graphene for supercapacitors
Nanowerk August 23, 2021 Supercapacitors, which have safe and fast charge (in seconds) and high energy storage are promising for consumer electronics, hybrid electric vehicles and industrial power management. Recently, laser scribed graphene has been increasingly studied for supercapacitor applications. With the laser scribing process, graphene can be directly fabricated and patterned for supercapacitors. Researchers in China summarize recent developments, current challenges and future advancements of supercapacitors based on laser scribed graphene. They summarize facile laser scribing methods for graphene and the application for electrochemical double-layer capacitors, pseudo-capacitors, and hybrid supercapacitors. Recent developments are discussed demonstrating that laser scribing technology […]
Flexible, easy-to-scale nanoribbons move graphene toward use in tech applications
Science Daily May 3, 2021 Silicon-based fiber optics are currently the best structures for high-speed, long distance transmissions, but graphene could improve performance even more. Researchers at the University of Wisconsin created a scalable fabrication technique to make the smallest graphene ribbon structures. They found that to improve graphene’s performance is to cut it into microscopic, nanometer-scale ribbon structures, which act as tiny antennas that interact with light. The smaller the antenna, the higher energies of light it interacts with. As the ribbon width decreases, so does the resonant wavelength of light. Lower wavelengths mean higher energies, and their devices interacted […]
A material keyboard made of graphene
Phys.org May 5, 2021 An international team of researchers (Switzerland, Japan) put two layers graphene flakes on top of each other and made a magic angle of exactly 1.06 degrees. The atomic crystal lattices of the graphene flakes created a moiré pattern. They attached several additional electrodes on top of the magic angle graphene flakes to apply an electric voltage to the material. By applying different voltages to the individual electrodes, they turned the magic angle graphene into an insulator in one spot, but a few hundred nanometres to one side it becomes a superconductor. For possible uses in quantum […]
Graphene and 2D materials could move electronics beyond ‘Moore’s Law’
Science Daily June 3, 2020 After the first demonstration of spin transport in graphene in 2007 at room temperature, it was quickly realized that this novel material was relevant for both fundamental spintronics and future applications. In this colloquium an international team of researchers (Switzerland, USA – Columbia University, Spain, Singapore, the Netherlands, UK) reviews recent theoretical and experimental advances on electronic spin transport in graphene and related 2D materials. They focus on emergent phenomena in van der Waals heterostructures and the new perspectives provided by them, including proximity-enabled spin-orbit effects, the coupling of electronic spin to light, electrical tunability, […]