EurekAlert August 1, 2019 An international team of researchers (USA – Rutgers University, Japan) studied twisted bilayer graphene, created by superimposing two layers of graphene and slightly misaligning them. This creates a “twist angle” that results in a moiré pattern which changes rapidly when the twist angle changes and have a dramatic effect on the electronic properties of the material. This is because the moiré pattern slows down the electrons that conduct electricity in graphene and zip past each other at great speeds. At a twist angle of about 1.1 degrees – the so-called magic angle – the electrons come […]
Tag Archives: Materials science
Experimental observation of a new class of materials: Excitonic insulators
Science Daily July 31, 2019 In a new study researchers in Australia have found evidence of a new phase of matter predicted in the 1960s: the excitonic insulator. It is a new phase of matter in the critical transition point between insulator and metal. The researchers studied antimony nanoflake using scanning tunneling microscopy and spectroscopy. They observed the unique feature of the excitonic insulator, a charge density wave (CDW) without periodic lattice distortion and a gap induced by the CDW near the Fermi surface, suggesting that the antimony (Sb(110)) nanoflake is an excitonic insulator. They are predicted to host many […]
Artificial intelligence (AI) designs metamaterials used in the invisibility cloak
EurelAlert July 14, 2019 Researchers in South Korea developed an AI system and taught it to design arbitrary photonic structures and gave additional level of freedom of the design by categorizing types of materials and adding them as a design factor, which made it possible to design appropriate materials for relevant optical properties. Previous studies required inputs of materials and structural parameters beforehand and adjusting photonic structures afterwards. The current process significantly reduced the time needed to design photonic structures…read more. Open Access TECHNICAL ARTICLE
Ultra-soft, liquid magnetic droplets could vault technology forward
Nanowerk July 18, 2019 Solid ferromagnetic materials are rigid in shape and cannot be reconfigured. Ferrofluids, although reconfigurable, are paramagnetic at room temperature and lose their magnetization when the applied magnetic field is removed. An international team of researchers (USA – Lawrence Berkeley Laboratory, UC Santa Cruz, UC Berkeley, UMass Amherst, China, Japan) shows a reversible paramagnetic-to-ferromagnetic transformation of ferrofluid droplets by the jamming of a monolayer of magnetic nanoparticles assembled at the water-oil interface. The ferromagnetic liquid droplets exhibit a finite coercivity and remnant magnetization, they can be easily reconfigured into different shapes while preserving the magnetic properties of […]
Extremely hard yet metallically conductive: Researchers develop novel material with high-tech prospects
Phys.org July 8, 2019 An international team of researchers (Germany, Russia, Sweden, USA – University of Chicago, France) has developed a route to scale up the synthesis of rhenium nitride pernitride through a reaction between rhenium and ammonium azide, in a large-volume press at 33 GPa. Although metallic bonding is typically seen incompatible with intrinsic hardness, Re2(N2)(N)2 turned to be at a threshold for super hard materials. The process can be used for the synthesis of other nitrides, in particular nitrides of transition metals, which could also have technologically important properties…read more. Open Access TECHNICAL ARTICLE
Researchers ‘stretch’ the ability of 2-D materials to change technology
Phys.org June 10, 2019 An international team of researchers (USA – University of Rochester, China) developed a platform and deposited a flake of molybdenum ditelluride (MoTe2) onto a ferroelectric material. When voltage is applied to the ferroelectric—which acts like a transistor’s third terminal, the 2-D material by the piezoelectric effect, causing it to stretch. When stretched, by about 0.4 percent, and unstretched, the MoTe2 changes from a low conductivity semiconductor material to a highly conductive semi metallic material and back again. It operates just like a field effect transistor. The process works at room temperature and requires only a small […]
Promising material could lead to faster, cheaper computer memory
Science Daily May 2, 2019 Bismuth ferrite (BiFeO3) has the potential to store information much more efficiently than is currently possible. However, its magnetoelectric response is small. Researchers at the University of Arkansas simulated conditions that enhance the magnetoelectric response to the point that it could be used to more efficiently store information by using electricity, rather than magnetism. They found additional oscillations consisting of a mixing between acoustic phonons, optical phonons, and magnons, and reflect the existence of a new quasiparticle that can be coined an “electroacoustic magnon.” The finding could help tune the samples to the magnetostrictive-induced mechanical […]
Mimicking squid skin to improve thermoregulating blankets
Physics World May 2, 2019 Squid skin contains embedded chromatophore organs that are packed with pigment granules. These cells contract and expand thereby changing the wavelengths of light they absorb and reflect. Inspired by the squid skin a team of researchers in the US (UC Irvine, industry) designed a composite thermoregulatory material made up of a soft and stretchable infrared-transparent polymer matrix covered with an array of infrared-deflecting metal domains stably anchored within the matrix. In the relaxed state, the materials reflect nearly all incoming infrared radiation. When stretched, however, the anchored metal domains move apart and uncover parts of […]
Lasers make magnets behave like fluids
Science Daily April 18, 2019 When a magnet is hit with a short enough laser pulse the spins within a magnet will no longer point just up or down, but in all different directions canceling out the metal’s magnetic properties. Using mathematical modeling, numerical simulations and experiments an international team of researchers (USA – University of Colorado, NIST, SLAC, Temple University, UK, Sweden, U, Italy, Germany, China, Japan, Belgium) has shown that the spins behaved like a superfluid 3 picoseconds after a laser pulse hits and then form small clusters with the same orientation like “droplets” in which the spins […]
Ultrafast Cluster Electronics
Next Bi Future April 12, 2019 Researchers in Japan combined quantum chemical and molecular dynamic calculations to predict how clusters of molecules behave and interact over time providing critical insight for future electronics. They used their method to predict the changes in a computer-simulated cluster of benzene molecules over time. When light is applied to the T-shaped benzene clusters, they reorganize themselves into a single stack; an interaction known as pi-stacking. This modification from one shape to another changes the cluster’s electrical conductivity, making it act like an on-off switch. They simulated the addition of a molecule of water to […]