Phys.org October 19, 2021 A team of researchers in the US (Case Western reserve University, Tufts University, Sandia National Laboratory) manipulated an “orientable Newtonian liquid,” in this case to a nematic liquid crystal that behaves predictably, i.e., linearly, when an outside stimulus is applied. They forced the liquid crystal/air interface to change shape merely by exploiting the orientability of the molecules that comprise the liquid crystal by placing a patterned substrate on the opposite side of a thin nematic film. By doing so, they were able to control the alignment of molecules throughout the material which resulted in the appearance […]
Tag Archives: Materials science
Unmasking the magic of superconductivity in twisted graphene
Science Daily October 20, 2021 An international team of researchers (USA – Princeton University, Japan) combined tunnelling and Andreev reflection spectroscopy with the scanning tunnelling microscope to observe several key experimental signatures for unconventional superconductivity in magic angle twisted bilayer graphene (MATBG). They showed that the tunnelling spectra below the transition temperature Tc are inconsistent with those of a conventional s-wave superconductor, but rather resemble those of a nodal superconductor with an anisotropic pairing mechanism. They observed a large discrepancy between the tunnelling gap which far exceeds the mean-field BCS ratio, and the gap extracted from Andreev reflection spectroscopy. The […]
Liquid metal proven to be cheap and efficient CO2 converter
Phys.org October 13, 2021 An international team of researchers (Australia, USA – UCLA, North Carolina State University) has developed technology to capture carbon that uses suspensions of gallium liquid metal to reduce CO2 into carbonaceous solid products and O2 at near room temperature. The nonpolar nature of the liquid gallium interface allows the solid products to instantaneously exfoliate, hence keeping active sites accessible. The solid co-contributor of silver-gallium rods ensures a cyclic sustainable process. The overall process relies on mechanical energy as the input, which drives nano dimensional triboelectrochemical reactions. When a gallium/silver fluoride mix at 7:1 mass ratio was […]
Researchers develop sensitive new way of detecting transistor defects
Nanowerk October 11, 2021 A team of researchers in the US (NIST, Pennsylvania State University) concentrated on the boundary, or channel, between the thin oxide layer and the bulk semiconductor body which controls the resistance of the device from source to drain. They used electrically detected magnetic resonance (EDMR) to detect defects in the channel. To focus exclusively on activity in the channel, researchers use a technique called bipolar amplification effect (BAE). The parameter of importance is the interface defect density, which is a number that describes how many defects are within some area of the semiconductor-oxide interface. The BAE […]
Induced flaws in quantum materials could enhance superconducting properties
Science Daily October 4, 2021 The properties of quantum materials are commonly tuned using experimental variables such as pressure, magnetic field, and doping. An international team of researchers (USA – University of Minnesota, Oak Ridge National Laboratory, Argonne National Laboratory, Croatia, China) has shown that compressive plastic deformation induces low-dimensional superconductivity well above the superconducting transition temperature (Tc) of undeformed SrTiO3, with evidence of possible superconducting correlations at temperatures two orders of magnitude above the bulk Tc. The enhanced superconductivity is correlated with the appearance of self-organized dislocation structures. They observed deformation-induced signatures of quantum-critical ferroelectric fluctuations and inhomogeneous ferroelectric […]
Scientists create material that can both move and block heat
Science Daily September 30, 2021 An international team of researchers (USA – University of Chicago, University of Illinois, Cornell University, Sweden) stacked ultra-thin layers of crystalline sheets on top of each other, but rotated each layer slightly, creating a material with atoms that are aligned in one direction but not in the other. They measured the results and found that a microscopic wall made of this material was extremely good at preventing heat from moving between compartments. They could transport heat along the wall very easily. Making computer chips smaller creates a high-power density environment. But if we can use […]
Twisted layers of MoS2 enable the engineering of novel states of matter
Nanowerk September 24, 2021 An international team of researchers (Germany, USA – Simons Foundation, University of Pennsylvania, Spain) has discovered that two twisted layers of MoS2 can be used to control kinetic energy scales in solids. In addition to using the twist angle to control the material’s electronic properties, they demonstrated that the electrons in MoS2 can interfere destructively, stopping their motion for certain paths making it possible to engineer exotic magnetic states. They studied the collective behavior of twisted bilayer MoS2 in the presence of interactions and characterized an array of different magnetic and orbitally-ordered correlated phases, which may […]
Unbreakable glass inspired by seashells
Phys.org September 28, 2021 Nacre, mother of pearl, made of stiff pieces of chalk-like matter that are layered with highly elastic soft proteins, has the rigidity of a stiff material and durability of a soft material. It is 3000 times tougher than the materials that compose it. An international team of researchers (Canada, USA- University of Colorado) took the architecture of nacre and replicated it with layers of glass flakes and acrylic, yielding an exceptionally strong yet opaque material that can be produced easily and inexpensively. They made the composite optically transparent. By tuning the refractive index of the acrylic, […]
Creating cotton that is fireproof and comfortable
Phys.org September 15, 2021 Researchers in Switzerland utilized a tri-functional phosphorous compound (trivinylphosphine oxide), which has the capability of reacting only with specifically added molecules (nitrogen compounds like piperazin) to form its own network inside cotton. This makes the cotton permanently fire-resistant without blocking the favorable -OH groups. This flame retardant treatment does not include carcinogenic formaldehyde. The phosphine oxide networks do not wash out. After 50 launderings, 95 percent of the flame retardant network was still present in the fabric. To fix the phosphine oxide networks inside the cellulose they treated the cotton with an aqueous solution of phosphorus […]
Magnetic field turns handed superconductor into liquid crystal-like nematic state
Nanowerk September 15, 2021 Recent measurements of the resistivity in magic-angle twisted bilayer graphene near the superconducting transition temperature show twofold anisotropy, or nematicity, when changing the direction of an in-plane magnetic field. This was interpreted as strong evidence for exotic nematic superconductivity instead of the widely proposed chiral superconductivity. An international team of researchers (Germany, USA – the Flatiron Institute, Spain) has suggested a surprising connection between the nematic behavior of a superconductor in a magnetic field and its spiral-like ground state in the absence of the field. Their theory could not only explain recent experiments on twisted bilayer […]