Archive for the ‘materials’ category: Page 116

Mar 1, 2021

Surprise in Solid-State Physics: Magnetic Effect Without a Magnet

Posted by in categories: materials, physics

Surprise in solid-state physics: The Hall effect, which normally requires magnetic fields, can also be generated in a completely different way – with extreme strength.

Electric current is deflected by a magnetic field – in conducting materials this leads to the so-called Hall effect. This effect is often used to measure magnetic fields. A surprising discovery has now been made at TU Wien, in collaboration with scientists from the Paul Scherrer Institute (Switzerland), McMater University (Canada), and Rice University (USA): an exotic metal made of cerium, bismuth, and palladium was examined and a giant Hall effect was found to be produced by the material, in the total absence of any magnetic field. The reason for this unexpected result lies in the unusual properties of the electrons: They behave as if magnetic monopoles were present in the material. These discoveries have now been published in the scientific magazine PNAS.

A voltage perpendicular to the current.

Feb 27, 2021

Michelin tyres will be 100% sustainable by 2050

Posted by in categories: materials, sustainability

By 2050, all Michelin tyres will be made entirely from renewable, recycled, biosourced or otherwise sustainable materials, the company announced this week.

Feb 21, 2021

Increasing optical data transmission speed

Posted by in categories: energy, materials

Pulsed lasers repeatedly emit light for a short period of time as if blinking. They have the advantage of focusing more energy than a continuous wave laser, whose intensity is kept unchanged over time. If digital signals are loaded in a pulsed laser, each pulse can encode one bit of data. In this respect, the higher the repetition rate, the more the amount of data that can be transmitted. However, conventional optical-fiber-based pulsed lasers have typically had a limitation in increasing the number of pulses per second above the MHz level.

The Korea Institute of Science and Technology (KIST) announced that the research team led by Senior Researcher Dr. Yong-Won Song at the Center for Opto-Electronic Materials and Devices was able to generate at a rate at least 10000 times higher than the state of the art. This achievement was accomplished by inserting an additional resonator containing graphene into a fiber-optic pulsed– oscillator that operates in the domain of femtoseconds (10-15 seconds). The data transmission and processing speeds are expected to increase significantly by applying this method to data communications.

The KIST research team noted that the characteristics of the wavelength and intensity of laser light that change over time are correlated (Fourier transform). If a resonator is inserted into the laser oscillator, the wavelength of the pulsed laser is periodically filtered, thereby modifying the pattern of laser intensity change. Based on this background research, Principal Researcher Song synthesized graphene, which has the characteristics of absorbing and eliminating weak light and amplifying the intensity by passing only strong light into the resonator. This allows the laser intensity change to be accurately controlled at a high rate, and thus the repetition rate of pulses could be increased to a higher level.

Feb 19, 2021

Twisted trilayer graphene could help make high-temperature superconductors

Posted by in categories: materials, particle physics

Two’s company, but three’s a crowd – unless you’re trying to make graphene superconduct at higher temperatures. That is the finding of researchers at Harvard University in the US, who discovered that the superconducting state in three stacked and twisted layers of graphene is more robust to temperature increase than the equivalent state in two-layer graphene. The researchers also found evidence that superconductivity in the trilayer system comes from strong interactions between electrons, rather than weak ones as in most conventional superconductors – corroborating a result reported a few days earlier by a separate team at the Massachusetts Institute of Technology (MIT).

A sheet of graphene consists of a simple repetition of carbon atoms arranged in a two-dimensional hexagonal lattice. When two sheets of graphene are placed atop each other and slightly misaligned, they form a moiré pattern, or “stretched” superlattice that dramatically changes the electronic interactions in the material compared to its pristine counterpart. The misalignment angle is critical: in 2018, the MIT group, led by Pablo Jarillo-Herrero, discovered a so-called “magic” angle of 1.1° where the material switches from an insulator to a superconductor. This means the twisted graphene can carry electrical current with no resistance below a superconducting transition temperature, Tc, of 1.7 K.

Feb 17, 2021

Researchers discover a new route to forming complex crystals

Posted by in category: materials

When materials reach extremely small size scales, strange things begin to happen. One of those phenomena is the formation of mesocrystals.

Feb 17, 2021

Researchers report switching material between semiconductor and metallic states

Posted by in category: materials

A group of researchers from the Fritz Haber Institute of the Max Planck Society and the Humboldt-Universität zu Berlin have found out that a semiconductor can be converted to a metal and back by light more easily and more quickly than previously thought. This discovery may increase the processing speed and simplify the design of many common technological devices.

Feb 15, 2021

Scientists Make “Magic Carpet” Hover Using Only Light

Posted by in category: materials

Researchers were able to cause two plastic trays to hover using only light — opening the doors to research unexplored parts of the sky.

Feb 14, 2021

Refreshing: Coca-Cola introduces 100% recycled bottles in the US

Posted by in category: materials

The new bottles will cut the company’s use of new plastic by over 20 percent in North America compared to 2018, it said.

Feb 12, 2021

Plastic trash can now be recycled into ultra-strong graphene

Posted by in categories: health, materials

Plastic decomposition is sped up by the flash Joule heating method.

The smart fabric is light, breathable, and can change how first-responders deal with sarin.

Max G. Levy, Science and Health Journalism.

Feb 9, 2021

Researchers control a magnet’s state

Posted by in categories: energy, materials

An international team led by researchers of Delft University of Technology (TU Delft) has managed to manipulate the magnetic state of a magnetic material by optically shaking it. The whole process happens within an extremely short time frame of less than a few picoseconds. In times of stalling efficiency trends of current technology, such atomically-driven ultrafast control of magnetism opens broad new vistas for information technology. The results, which have been published in Nature Materials, could eventually lead to fast and energy-efficient data processing technologies, which are essential to keep up with our data hunger.