Technical / Research

Researchers from ETH Zurich in Switzerland and National Institute for Materials Science in Japan have used a nanoscale scanning magnetometer to image a distinctive hydrodynamic transport pattern—stationary current vortices—in a monolayer graphene device at room temperature. 

By measuring devices with increasing characteristic size, the team observed the disappearance of the current vortex and thus verified a prediction of the hydrodynamic model. they further observed that vortex flow is present for both hole- and electron-dominated transport regimes but disappears in the ambipolar regime. 

Researchers at the Massachusetts Institute of Technology (MIT), University of Texas at Dallas and Japan's National Institute for Materials Science have reported the quantum anomalous Hall effect (QAHE), a topological phenomenon that features quantized Hall resistance at zero magnetic field, in a rhombohedral pentalayer graphene-monolayer tungsten disulfide (WS2) heterostructure. 

This achievement can also be described as a 'five-lane superhighway' for electrons, that could allow ultra-efficient electronics and more. The team explained that its discovery could have direct implications for low-power electronic devices because no energy is lost during the propagation of electrons, which is not the case in regular materials where the electrons are scattered.

Researchers from the University of Cambridge, Tokyo Institute of Technology, University of Warwick and University of Namur have proposed a new materials theory based on "Murray's Law," applicable to a wide range of hierarchical structures, shapes and generalized transfer processes. 

The scientists experimentally demonstrated optimal flow of various fluids in hierarchically planar and tubular graphene aerogel structures to validate the proposed law. By adjusting the macroscopic pores in such aerogel-based gas sensors, they also showed a significantly improved sensor response dynamics. 

Researchers from Pohang University of Science and Technology (POSTECH), Korea Institute of Industrial Technology and Konkuk University have reported the development of a small-scale energy storage device capable of stretching, twisting, folding, and wrinkling. 

Nine MSC units connected in three parallel and three series. Image from npj Flexible Electronics

Micro supercapacitors (MSCs) have emerged as a promising candidate for deformable energy storage, due to high-power density, rapid charging, and long cycle life. However, the fabrication of interdigitated electrode patterns capable of maintaining the energy storage performance under repeated stretching and twisting has remained a great challenge, because brittle materials like gold (Au) have been commonly used as an electrode.

An international team of researchers, led by the University of Manchester, has achieved robust superconductivity in high magnetic fields using a newly created one-dimensional system. Achieving superconductivity in the quantum Hall regime has been a longstanding challenge, which this recent work aimed to address. 

The team followed the conventional route where counterpropagating edge states were brought into close proximity to each other. However, this approach was found to be limited. “Our initial experiments were primarily motivated by the strong persistent interest in proximity superconductivity induced along quantum Hall edge states,” explained University of Mnchester's Dr. Barrier, the paper’s lead author. “This possibility has led to numerous theoretical predictions regarding the emergence of new particles known as non-abelian anyons.”

Researchers from the University of Göttingen, Japan's National Institute for Materials Science and Massachusetts Institute of Technology (MIT) have demonstrated experimentally that electrons in naturally occurring double-layer graphene move like particles without any mass, in the same way that light travels. Furthermore, they have shown that the current can be "switched" on and off, which has potential for developing tiny, energy-efficient transistors. 

Among its many unusual properties, graphene is known for its extraordinarily high electrical conductivity due to the high and constant velocity of electrons travelling through this material. This unique feature has made scientists try to use graphene for faster and more energy-efficient transistors. The challenge has been that to make a transistor, the material needs to be controlled to have a highly insulating state in addition to its highly conductive state. In graphene, however, such a "switch" in the speed of the carrier cannot be easily achieved. In fact, graphene usually has no insulating state, which has limited graphene's potential a transistor.

Researchers from the National University of Singapore (NUS), and Czech Academy of Sciences recently developed a new design concept for creating next-generation carbon-based quantum materials, in the form of a tiny magnetic nanographene with a unique butterfly-shape hosting highly correlated spins. This new design has the potential to accelerate the advancement of quantum materials which are pivotal for the development of quantum computing technologies.

A visual impression of the magnetic “butterfly” hosting four entangled spins on “wings” (left) and its corresponding atomic-scale image obtained using scanning probe microscopy (right). Image credit: NUS

Magnetic nanographene, a tiny structure made of graphene molecules, exhibits remarkable magnetic properties due to the behavior of specific electrons in the carbon atoms’ π-orbitals. By precisely designing the arrangement of these carbon atoms at the nanoscale, control over the behavior of these unique electrons can be achieved. This renders nanographene highly promising for creating extremely small magnets and for fabricating fundamental building blocks needed for quantum computers, called quantum bits or qubits.

Researchers from Princeton University, University of California, Lawrence Berkeley National Laboratory and Japan's National Institute for Materials Science have used a special kind of microscope and two pieces of extremely defect-free graphene to capture the clearest and most direct images of a “Wigner crystal”, a structure made entirely of electrons.

Imaging a “Wigner crystal” is extremely hard. At room temperature, electrons can flow together in electric currents because their kinetic energy overcomes the force that makes particles with the same electric charge repel each other. At very low temperatures, however, repulsive electric forces win out, and the electrons end up arranging themselves into a uniform grid, or a crystal. Physicist Eugene Wigner predicted this phenomenon in 1934, but researchers only recently started to understand how to create Wigner crystals in the lab. 

Researchers from  Purdue University, University of California, Lawrence Berkeley National Laboratory and Japan's National Institute for Materials Science have managed to electrically manipulate a ‘chiral interface state’ in twisted monolayer-bilayer graphene, with potential for energy-efficient microelectronics and quantum computing.

The international research team, led by Lawrence Berkeley National Laboratory (Berkeley Lab), has taken the first atomic-resolution images and demonstrated electrical control of a chiral interface state – an exotic quantum phenomenon that could help researchers advance quantum computing and energy-efficient electronics.

A team from the National Hospital for Paraplegics (SESCAM), in collaboration with the Materials Science Institute of Madrid (ICMM-CSIC), has shown how new cell culture devices based on graphene oxide maintain the anti-inflammatory function of myeloid suppressor cells (MDSCs) once isolated from the donor's body. This function could be crucial for advancing cellular therapy beneficial to people with multiple sclerosis. 

"To exert their inflammation-controlling function in diseases such as multiple sclerosis, myeloid suppressor cells must maintain a very immature state. However, when extracted from the bone marrow and cultured in the laboratory, they begin to mature, losing their immunosuppressive activity, rendering them unsuitable for potential cellular therapy for patients with this type of neurodegenerative disease," explains Diego Clemente, a researcher at the National Hospital for Paraplegics and one of the lead authors of the study.