Science Daily September 16, 2020 A team of researchers in the US (Michigan Technological University, Argonne National Laboratory) explain the quantum and crystallographic origins of a novel surface effect in nonreciprocal optics that improves the processing of optical signals. They found significant differences in the ionic structure between surface and bulk in bismuth-substituted iron garnet materials. They found that the unit cell is elongated normal to the surface, thus enlarging the separation between Fe3+ ions. These ions play a central role in the magneto-optic response of this material. A marked displacement of Fe ions creates gaps at the surface that […]
Tag Archives: Materials science
New way of controlling conductivity of materials at the nanoscale
Science Daily September 16, 2020 Scientists routinely manipulate the flow of electrons to make possible smaller components in computers and mobile phones that use barely any electricity. However, some of the most promising concepts seem mutually exclusive inhibiting the creation of a network. An international team of researchers (Norway, Spain, Switzerland, USA – Lawrence Berkeley National Laboratory, UK, Finland) has developed a new approach based on exploiting ‘hidden’ irregularities at the atomic level, anti-Frenkel defects. Anti-Frenkel defects can be manipulated in such a way that changes in the conductivity do not affect the actual structure of the material or change […]
Physicists discover new magnetoelectric effect
Science Daily September 14, 2020 An international team of researchers (Austria, Russia, the Netherlands) found that in langasite made of lanthanum, gallium, silicon and oxygen, doped with holmium atoms even small changes in the direction of the magnetic field can switch the electrical properties of the material to a completely different state even though it has a crystal structure that is so symmetrical that it should actually not allow any magnetoelectric effect for theoretical reasons. In the case of weak magnetic fields there is no coupling whatsoever with the electrical properties of the crystal. But if the strength of the […]
Chemists develop a new type of one-molecule thick water-repellent film
Nanowerk September 9, 2020 An international team of researchers (Russia, Belarus) developed 0.8-1.5 nm thick calixarene-based films that can work as water-repellent coatings. Calixarenes are large bowl-shaped organic molecules that consist of several rings. The outer ring of the bowl is hydrophilic, and the innermost ring is hydrophobic. Their durability can be increased with UV radiation. The films can be used to create protective hydrophobic or anti-corrosion coatings for organic electronics or to develop molecular filters…read more. TECHNICAL ARTICLE
Nanoearthquakes control spin centers in SiC
Science Daily September 4, 2020 An international team of researchers (Germany, Russia) demonstrated the use of elastic vibrations to manipulate the spin states of optically active color centers in SiC at room temperature. They used a surface acoustic wave cavity to selectively address spin transitions with magnetic quantum number differences of ±1 and ±2 in the absence of external microwave electromagnetic fields. These spin-acoustic resonances reveal a nontrivial dependence on the static magnetic field orientation, which is attributed to the intrinsic symmetry of the acoustic fields combined with the peculiar properties of a half-integer spin system. These findings establish silicon […]
Molecule to store solar energy developed
Science Daily August 31, 2020 An international team of researchers (Sweden, Hungary, India) has developed a molecule belonging to the molecular photoswitches group that can take on two different forms: a parent form that can absorb energy from sunlight, and an alternative form where the structure of the parent form is changed to become much more energy-rich, while remaining stable. Through calculations they show that the molecule would undergo the desired change within 200 femtoseconds. The concept of switching between aromatic and non-aromatic states of a molecule has a major potential in the field of molecular photoswitches. A possible long-term […]
Black silicon photodetector breaks the 100% efficiency limit
Phys.org August 14, 2020 Ultraviolet sensors are utilized in numerous fields although their performance is surprisingly poor. An international team of researchers (Finland, Spain, Germany) used a nanostructured silicon photodiode with self-induced junction to demonstrate that it is possible to make a device with a certified external quantum efficiency above 130% in UV range without external amplification. They showed that the high efficiency is based on effective utilization of multiple carrier generation by impact ionization taking place in the nanostructures. While the results can readily have a significant impact on the UV-sensor industry, the underlying technological concept can be applied […]
Insect wings inspire new ways to fight superbugs
EurekAlert August 18, 2020 New anti-bacterial surfaces are being developed, featuring different nanopatterns that mimic the deadly action of cicadas and dragonflies’ wings. In a review article an international team of researchers (Australia, Spain, USA – Ohio State University, UK) has detailed exactly how these patterns destroy bacteria – stretching, slicing, or tearing them apart. They point out that different species have wings that are better at killing some bacteria than others, the wing surfaces have different density, height, and diameter of the nanopillars. The nanostructured surfaces could be used in medical or industrial applications…read more. TECHNICAL ARTICLE
A new iron based super elastic alloy capable of withstanding extreme temperatures
EurekAlert August 20, 2020 Researchers in Japan have discovered novel iron-based super elastic alloy (SEA) made of Fe-Mn-Al-Cr-Ni whose controllable temperature dependence goes from positive to negative, it is capable of withstanding extreme temperatures -both high and low. Increasing the amount of Chromium allowed the researchers to change the temperature dependence from a positive to a negative. Balancing the Chromium content resulted in zero temperature dependence with the critical stress remaining almost constant at various temperatures. The discovery possesses wide-spread application for outer-space exploration given the large temperature fluctuations that occur. It can potentially be used in tension braces in […]
Double layer of 2D materials unlocks crucial properties
Nanowerk August 10, 2020 The interactions between the different layers in structures, held together by van der Waals forces, can give rise to entirely new properties. An international team of researchers (Switzerland, France, Japan) has succeeded in creating such a structure using double layer of molybdenum disulfide sandwiched between an insulator and the electrical conductor graphene on each side. If a voltage is applied to the outer graphene layers it generates an electric field that affects the absorption properties of the two molybdenum disulfide layers. By adjusting the voltage applied wavelengths at which the electron-hole pairs are formed in these […]