Science Daily October 18, 2023 Multiferroics have multifunctional electrical and magnetic device applications. Two-dimensional materials with honeycomb lattices offer opportunities to engineer unconventional multiferroicity. Orbital multiferroics could offer strong valley–magnetic couplings and large responses to external fields—enabling device applications such as multiple-state memory elements and electric control of the valley and magnetic states. An international team of researchers (USA – MIT, Harvard University, Japan) has shown orbital multiferroicity in Penta layer rhombohedral graphene. They observed anomalous Hall signals Rxy with an exceptionally large Hall angle and orbital magnetic hysteresis at hole doping. There were four such states with different valley […]
Further evidence of Earth’s core leaking found on Baffin Island
Phys.org October 20, 2023 High 3He/4He ratios are thought to derive from the solar nebula or from solar-wind-irradiated material that became incorporated into Earth during early planetary accretion. Traditionally, this high-3He/4He component has been considered intrinsic to the mantle, having avoided outgassing caused by giant impacts and billions of years of mantle convection. A team of researchers in the US (Woods Hole Oceanographic Institution, Caltech) has shown the highest magmatic 3He/4He ratio in terrestrial igneous rocks, in olivines from Baffin Island lavas. According to them the extremely high-3He/4He helium in these lavas might have been derived from Earth’s core. The […]
Itinerant magnetism and superconductivity in exotic 2D metals for next-generation quantum devices
Phys.org October 23, 2023 Metallic ferromagnets with strongly interacting electrons often exhibit remarkable electronic phases such as ferromagnetic superconductivity, complex spin textures, and nontrivial topology. A team of researchers in the US (UC Berkeley, Los Alamos National Laboratory) conducted a series of experiments with a new type of layered 2D metal, finding connections in electronic behavior that might potentially be useful for fabricating complex superconducting quantum processors. They discussed the synthesis of a layered magnetic metal NiTa4Se8 (or Ni1/4TaSe2) with a Curie temperature of 58 Kelvin. Magnetization data and density functional theory calculations indicated that the nickel atoms host uniaxial […]
New noble-metal-free electrocatalyst decreases the energy required to generate hydrogen gas from water
Phys.org October 19, 2023 Generating hydrogen gas from clean sources, such as the splitting of water molecules with electricity through electrolysis, is important to achieving future carbon neutrality, but current methods are inefficient and limit the commercial practicality of hydrogen-based technologies. Researchers in Malaysia created electrocatalyst WS2/N-rGO/CC on a carbon cloth that was bound to reduced graphene oxide (rGO), a two-dimensional lattice semiconductor, combined with a very small amount of nitrogen to alter the properties of the reduced graphene oxide semiconductor. Hydrothermal reaction converted 2D WS2 into microscopic, three-dimensional nanoflowers that increased the surface area of the electrocatalyst to improve […]
Plant-based materials give ‘life’ to tiny soft robots
Science Daily October 23, 2023 Introducing anisotropic properties, and shape-change programmability to responsive hydrogels promises a host of opportunities in the development of soft robots. An international team of researchers (Canada, Germany) synthesized pH-responsive hydrogel nanocomposites with predetermined microstructural anisotropy, shape-transformation, and self-healing. They were largely composed of zwitterionic monomers and asymmetric cellulose nanocrystals. While the zwitterionic nature of the network imparted both self-healing and cytocompatibility to the hydrogel nanocomposites, the shear-induced alignment of cellulose nanocrystals rendered their anisotropic swelling and mechanical properties. They utilized a cut-and-paste approach to program reversible, and complex deformation into the hydrogels. As a proof-of-concept, […]
Researchers create the most water-repellent surface ever
Nanowerk October 23, 2023 Surface heterogeneity is generally acknowledged as the major cause of increased contact angle hysteresis and contact line friction of droplets. An international team of researchers (Finland, Japan) have shown that tuning the coverage of self-assembled monolayers (SAMs), water contact angles changed gradually from about 10° to 110° yet contact angle hysteresis and contact line friction were low for the low-coverage hydrophilic SAMs as well as high-coverage hydrophobic SAMs. Their slipperiness was not expected based on the substantial chemical heterogeneity of the SAMs featuring uncoated areas of the substrate well beyond the size of a water molecule […]
Scientists isolate early-warning tremor pattern in lab-made earthquakes
Phys.org October 25, 2023 An international team of researchers (USA – UT Austin, Pennsylvania State University, University of Nevada, Italy) measured waveform similarity and pairwise differential travel-times (DTT) between acoustic emission (AEs) throughout the seismic cycle. AEs broadcasted prior to slow labquakes had small DTT and high waveform similarity relative to fast labquakes. They showed that during slow stick-slip, the fault never fully locked, and waveform similarity and pairwise differential travel times did not evolve throughout the seismic cycle. In contrast, fast laboratory earthquakes were preceded by a rapid increase in waveform similarity late in the seismic cycle and a […]
Shape-shifting fiber can produce morphing fabrics
MIT News October 26, 2023 A team of researcher in the US (MIT, Northeastern University) has developed programmable, actuating fiber they call FibeRobo which contracts in response to an increase in temperature, then self-reverses when the temperature decreases, without any embedded sensors or other hard components. Unlike other actuating threads explored in HCI FibeRobo exhibits rapid thermal self-reversing actuation with large displacements (∼40%) without twisting. A reproducible UV fiber drawing setup produces hundreds of meters of fiber with a sub-millimeter diameter, and FibeRobo is fully compatible with existing textile manufacturing machinery such as weaving looms, embroidery, and industrial knitting machines. […]
Silk nanointerfaces merge biology and electronics
Nanowerk October 24, 2023 Researchers at Tufts University have developed a hybrid biopolymer–semiconductor device by integrating nanoscale silk layers in a well-established class of inorganic field-effect transistors (silk-FETs). The devices offered two distinct modes of operation—either traditional field-effect or electrolyte-gated—enabled by the precisely controlled thickness, morphology, and biochemistry of the integrated silk layers. The different operational modes were selectively accessed by dynamically modulating the free-water content within the nanoscale protein layer from the vapor phase. They illustrated the utility of the hybrid devices in a highly sensitive and ultrafast breath sensor, highlighting the opportunities offered by the integration of nanoscale […]
A step on the way to solid-state batteries
Nanowerk October 24, 2023 Researchers at MIT have introduced Li-garnet Li7La3Zr2O12−d (LLZO) as a suitable ceramic due to its high Li+ conductivity and wide electrochemical stability window. However, high sintering temperatures raise concerns about the cathode interface stability, production costs, and energy consumption for scalable manufacture. They developed a “sinter-free” route to stabilize cLLZO as films at half of its sinter temperature. They established a time-temperature-transformation (TTT) diagram which captured the amorphous-to-crystalline LLZO transformation based on crystallization enthalpy analysis and confirmed stabilization of thin-film cLLZO at record low temperatures of 500 °C. According to the researchers their findings pave the way […]