Phys.org May 14, 2018 In their electronically excited state Möbius aromatic molecules display “antiaromaticity,” characterized by high energy levels and high instability. To understand their properties, researchers in Japan applied a time-resolved electron paramagnetic resonance method to detect the magnetic properties of a reactive intermediate molecule hexaphyrin. Illuminating hexaphyrin with laser pulses, they detected the resonance between the microwave and the electron spins linked to the magnetism of the excited triplet state and to the external magnetic field. The findings has application in the use of these special properties to electronic functional materials, such as organic solar cells and electric […]
Tag Archives: Advanced materials
Making new layered superconductors using high entropy alloys
Science Daily May 4, 2018 Use of layered materials with a molecular structure consisting of alternating superconducting layers and “blocking layers” acting as insulating spacers is used to design new superconductors that retain superconducting properties at higher temperatures. Researchers in Japan have created new superconductors made of layers of bismuth sulfide and a high entropy rare earth alloy oxyfluoride, containing five rare earth elements – lanthanum, cerium, praseodymium, neodymium, and samarium – at the same crystallographic site. The new material retains superconducting properties over a wider range of lattice parameters than materials without high-entropy-alloy states. The work promises a new […]
Engineers develop technique to make adaptive materials
Science Daily April 17, 2018 A team of researchers in the US (ARL, University of Maryland) attached ultraviolet light reactive molecules to reinforcing agents, like carbon nanotubes, and embedded them in a polymer. When exposed to ultraviolet light, a chemical reaction occurs such that the interaction between the reinforcing agents and the polymer increases, making the material stiffer and stronger. In their experiment the materials became 93-percent stiffer and 35-percent stronger after a five-minute exposure to ultraviolet light. Applications include remote shaping of structural materials, adaptive soft robotics, and tunable intrinsic material damping… read more. TECHNICAL ARTICLE
Graphene sets a new record on squeezing light to one atom
Science Daily April 20, 2018 An international team of researchers (Spain, France, Portugal, USA – MIT) has shown that a graphene-insulator-metal heterostructure can overcome energy loss and demonstrate plasmon confinement down to the ultimate limit of the length scale of one atom. This is achieved through far-field excitation of plasmon modes squeezed into an atomically thin hexagonal boron nitride dielectric spacer between graphene and metal rods. A theoretical model that takes into account the nonlocal optical response of both graphene and metal is used to describe the results. These ultraconfined plasmonic modes, addressed with far-field light excitation, enable a route […]
From insulator to conductor in a flash
Nanowerk April 16, 2018 An international team of researchers (Russia, UK, Germany) has devised a method to study extremely fast phase transitions in Mott insulators. Their theory involves firing extremely short tailored laser pulses at a material to observe how the electrons in the material are excited into motion and emit resonant vibrations at specific frequencies, as harmonics of the incident light. By analysing the high harmonic spectrum, they could observe the change in the structural order in the materials. Such phase transitions should allow us to develop entirely new switching elements for the next-generation electronics that are faster and […]
Novel thermal phases of topological quantum matter in the lab
Phys.org April 18, 2018 Using quantum simulators, an international team of researchers (Spain, USA – MIT, Harvard University, Switzerland) replicated topological insulators at finite temperature and measured their topological quantum phases and complete phase diagram including environmental effects. The proposed measurement scheme does not involve prior knowledge of the system state and it is extensible to interacting particles and topological models with a large number of bands. The research advances the synthesis and control of topological matter using quantum technologies. Among other applications, topological quantum matter could be used as hardware for future quantum computers… read more. Open Access TECHNICAL […]
Finding order in disorder demonstrates a new state of matter
Science Daily April 2, 2018 In artificial spin ice, which in certain phases appears disordered, the material is ordered, but in a “topological” form. A team of researchers in the US (University of Illinois at Urbana-Champaign, Los Alamos National Laboratory, University of Illinois at Urbana-Champaign, Lawrence Berkeley National Laboratory, University of Minnesota, Yale University) explored a particular artificial spin ice geometry, called Shakti spin ice which could reach its low-energy state as temperature was reduced in successive quenches. Shakti spin ice stubbornly remained at about the same energy level that could be mapped exactly into the “dimer cover model,” whose […]
Self-assembling, tunable interfaces found in quantum materials
Phys.org March 27, 2018 Extensive research has shown that at interfaces between two materials, the remarkable properties of quantum materials can be strongly enhanced, or entirely new functional properties may arise. An international team of researchers (USA – Los Alamos National Laboratory, University of Tennessee, NIST, Oak Ridge National Laboratory, UK, Germany) has demonstrated that in certain metals, the competition between various interactions may be resolved by the spontaneous formation of a state in which the electronic and magnetic properties alternate periodically. The spontaneously self-assembling interfaces are intrinsically clean, and relevant parameters such as the interface thickness can be tuned […]
Graphene flakes for future transistors
Science Daily March 14, 2018 Researchers in Italy have demonstrated that hexagonal graphene nanoflakes with zigzag edges display quantum interference. In “Quantum interference transistors” destructive interference would be the “OFF” status. For the “ON” status, they say it is sufficient to remove the conditions for interference. They also demonstrated that magnetism emerges spontaneously at their edges, without any external intervention. This enables the creation of a spin current. The union between the phenomena of quantum interference and of magnetism would allow to obtain almost complete spin polarization, with a huge potential in the field of spintronics. These properties could be […]
Research team creates hydrogel adhesives to seal wounds
Physorg March 9, 2018 Researchers at Harvard University have developed a hydrogel which is a hybrid of two different polymers: a seaweed extract called alginate and polyacrylamide. When these become entangled with each other, they create a molecular network that demonstrates unprecedented toughness and resilience for a hydrogel material—on par with the body’s natural cartilage. When combined with an adhesive layer containing positively charged polymer molecules, the resulting hybrid material can bind to tissues, stretch up to 20 times its initial length, and attach to wet tissue surfaces undergoing dynamic movement… read more.