MIT News March 28, 2024 An international team of researchers (USA – MIT, NOAA, UC San Diego, China, UK, Australia) used long-term atmospheric observations to determine SF6 emissions from China between 2011 and 2021 to evaluate the Chinese national SF6 emission inventory and to better understand the global SF6 budget. SF6 emissions in China substantially increased in 2021. The increase was larger than the global total emissions rise. Emissions in the less-populated western regions of China contributed significantly to the national SF6 emissions. The CO2-eq emissions of SF6 in China in 2021 were 125 million tonnes, comparable to the national […]
Intelligent liquid
Nanowerk April 4, 2024 Traditionally the building blocks of metamaterials are arranged in fixed positions within a lattice structure. An international team of researchers (USA – Harvard University, Israel) showed that by mixing highly deformable spherical capsules into an incompressible fluid, it is possible to realize a ‘metafluid’ with programmable compressibility, optical behaviour, and viscosity. Experimentally and numerically, they demonstrated that the buckling of the shells endows the fluid with a highly nonlinear behaviour. They harnessed this behaviour to develop smart robotic systems, highly tunable logic gates and optical elements with switchable characteristics. They demonstrated that the collapse of the […]
Magnetic avalanche triggered by quantum effects: ‘Barkhausen noise’ detected for first time
Phys.org March 28, 2024 Most macroscopic magnetic phenomena (including magnetic hysteresis) are typically understood classically. An international team of researchers (USA – Caltech, University of Colorado, University of Chicago, University of Tennessee, Canada, Japan, UK) examined the dynamics of a uniaxial rare-earth ferromagnet deep within the quantum regime, so that domain wall motion, and the associated hysteresis, was initiated by quantum nucleation, which then grew into large-scale domain wall motion, that was observable as an unusual form of Barkhausen noise. They found that the “quantum Barkhausen noise” exhibited two distinct mechanisms for domain wall movement, each of which was quantum-mechanical, […]
New hydrogel can stretch to 15 times its original size
Phys.org March 29, 2024 Hyper elastic materials exhibit a nonlinear elastic response to large strains, whereas hydrogels typically possess a low elastic range due to the nonuniform cross-linking and limited chain segments among cross-links. An international team of researchers (USA, China) developed a hyperplastic hydrogel that possesses a broader elastic range by introducing a reversible pearl-necklace structure, in which beads are connected by strings. The subnanometric beads could efficiently unfold and refold under cyclic mechanical strains; thus, the hydrogel could rapidly recover after being stretched to an aerial strain of more than 10,000%. It could quickly heal from minor mechanical […]
Research team realizes magnonic frequency comb
Phys.org April 1, 2024 A direct analog of frequency combs in the magnonic systems has not been demonstrated to date. Researchers in China generated a new magnonic frequency comb in the resonator with giant mechanical oscillations through the magnomechanical interaction. It contained up to 20 comb lines, which were separated by the mechanical frequency of 10.08 MHz. The thermal effect based on the strong pump power induced the cyclic oscillation of the magnon frequency shift, which led to a periodic oscillation of the magnonic frequency comb. They demonstrated the stabilization and control of the frequency spacing of the magnonic frequency […]
Researchers determine structure of new metal tellurate material with potential uses in solar energy and more
Phys.org April 3, 2024 An international team of researchers (Austria, Sweden, Canada, Finland) grew crystals of CoTeO4 crystals by the application of chemical vapor transport reactions in closed silica ampoules, starting from polycrystalline material in a temperature gradient with TeCl4 as transport agent. Crystal structure analysis of CoTeO4 showed noticeable improvement over the statistical significance and accuracy of the previously reported structural model. CoTeO4 did not undergo a structural phase transition upon heating, but decomposed stepwise (Co2Te3O8 as intermediate phase) to Co3TeO6 as the only crystalline phase stable above 770 °C. Temperature-dependent magnetic susceptibility and dielectric measurements suggested antiferromagnetic ordering […]
Researchers discover dual topological phases in an intrinsic monolayer crystal
Phys.org April 2, 2024 Introducing electron correlations to a quantum spin Hall (QSH) insulator can lead to the emergence of a fractional topological insulator and other exotic time-reversal-symmetric topological order, not possible in quantum Hall and Chern insulator systems. An international team of researchers (USA – Boston College, Harvard University, UCLA, Texas A&M, University of Tennessee, MIT, Singapore, Japan, China, Canada) has found a new dual QSH insulator within the intrinsic monolayer crystal of TaIrTe4, arising from the interplay of its single-particle topology and density-tuned electron correlations. At charge neutrality, monolayer TaIrTe4 demonstrated the QSH insulator, manifesting enhanced nonlocal transport […]
Room-temperature 2D magnet: Electronic-structure insights
Nanowerk March 28, 2024 Iron gallium telluride (Fe3GaTe2), a van der Waals ferromagnet, demonstrated intrinsic ferromagnetism above room temperature. An international team of researchers (USA – Lawrence Livermore National Laboratory, South Korea, China) revealed the electronic structure of Fe3GaTe2 in its ferromagnetic ground state establishing a consistent correspondence between the measured band structure and theoretical calculations, underscoring the significant contributions of the Heisenberg exchange interaction (Jex) and magnetic anisotropy energy to the development of the high-TC ferromagnetic ordering in Fe3GaTe2. They observed substantial modifications to these crucial driving factors through doping, which they attributed to alterations in multiple spin-splitting bands […]
‘Shear sound waves’ provide the magic for linking ultrasound and magnetic waves
Phys.org March 29, 2024 An international team of researchers (Japan, Austria, Spain) observed strong coupling between magnons and surface acoustic wave (SAW) phonons in a thin CoFeB film constructed in an on-chip SAW resonator by analyzing SAW phonon dispersion ant crossings. They used a nanostructured SAW resonator design that allowed them to enhance shear-horizontal strain. This type of strain couples strongly to magnons. Their device design provided the tunability of the film thickness with a fixed phonon wavelength, which was a departure from the conventional approach in strong magnon-phonon coupling research. They detected a monotonic increase in the coupling strength […]
Simple equations clarify cloud climate conundrum
Phys.org April 1, 2024 Changes in anvil clouds with warming remain a leading source of uncertainty in estimating Earth’s climate sensitivity. An international team of researchers (France, UK) developed a feedback analysis that decomposes changes in anvil clouds and creates testable hypotheses for refining their proposed uncertainty ranges with observations and theory. They derived a simple but quantitative expression for the anvil area feedback, which depended on the present-day measurable cloud radiative effects and the fractional change in anvil area with warming. Satellite observations suggested an anvil cloud radiative effect of about ±1 W m−2, which requires the fractional change in anvil […]