Phys.org September 27, 2024 Excitons in monolayer semiconductors offer strong light–matter coupling, spin–valley locking and exceptional tunability allowing electrical switching of their optical response due to efficient interactions of excitonic emitters with free charge carriers forming trions and Fermi polarons. However, there are major limitations to how fast the light emission of these states can be tuned, restricting most applications to an essentially static regime. An international team of researchers (Italy, Sweden, Germany, Japan) demonstrated switching of excitonic light emitters in monolayer semiconductors on ultrafast picosecond time scales by applying short pulses in the terahertz spectral range following optical injection. […]
Researchers crack a key problem with sodium-ion batteries for electric vehicles and grid energy storage
Phys.org September 27, 2024 Microstrain and the associated surface-to-bulk propagation of structural defects are known to be major roadblocks for developing high-energy and long-life batteries. However, the origin and effects of microstrain during the synthesis of battery materials remain largely unknown. A team of researchers in the US (Argonne National Laboratory, Brookhaven National Laboratory) performed microstrain screening during real-time and realistic synthesis of sodium layered oxide cathodes and gathered evidence from multiscale in situ synchrotron X-ray diffraction and microscopy characterization. They found that the spatial distribution of transition metals within individual precursor particles strongly governed the nanoscale phase transformation, local […]
Researchers create orientation-independent magnetic field-sensing nanotube spin qubits
Phys.org October 2, 2024 Optically addressable spin defects in 3D crystals and 2D van der Waals (vdW) materials are important for nanoscale quantum sensing. However, optically detected magnetic resonance of localized spin defects in a nanotube has not been observed. A team of researchers in the US (Purdue University, Indiana University) found single spin color centers in boron nitride nanotubes (BNNTs) at room temperature which suggested that BNNT spin defects possess a spin S = 1/2 ground state without an intrinsic quantization axis, leading to orientation-independent magnetic field sensing. Using this unique feature, they observed anisotropic magnetization of a 2D […]
Researchers observe hidden deformations in complex light fields
Phys.org October 1, 2024 When reflected from an interface, a laser beam generally drifts and tilts away from the path predicted by ray optics, an intriguing consequence of its finite transverse extent. For twisted light, such beam shifts manifest even more dramatically: upon reflection, a field containing a high-order optical vortex is expected to experience not only geometrical shifts, but an additional splitting of its high-order vortex into a constellation of unit-charge vortices, a phenomenon known as topological aberration. In an experiment an international team of researchers (Finland, Brazil) observed topological aberration effect verified through the deformation of vortex constellations […]
Scientists demonstrate advanced low-coherence BOCDR system using periodic pseudo-random modulation
Phys.org October 1, 2024 Brillouin optical correlation-domain reflectometry (BOCDR) is a technique for measuring the distribution of strain and temperature along an optical fiber. However, it faces a trade-off between spatial resolution and measurement range. Researchers in Japan proposed low-coherence BOCDR based on periodic pseudo-random modulation to address this issue and demonstrated its proof-of-concept operation. First, the dependence of the light source output spectrum on modulation parameters was investigated showing the potential to resolve the trade-off between spatial resolution and measurement range. They also demonstrated the capability of measuring strain distribution along optical fibers without a variable delay line under […]
Scientists uncover light absorbing properties of achiral materials
Phys.org September 30, 2024 In chiral metasurfaces, the lack of symmetry leads to differential absorption when probed with chiral light either in the form of circular polarization or helical phase fronts. Researchers in Canada demonstrated differential absorption of asymmetric twisted light beams, known as helical dichroism, which exist in an array and a single achiral structure and could be controlled. When extended to chiral structures, these asymmetrical chiral light modes enabled enhancing and tuning chiroptical sensitivity. According to the researchers their technique offers more control parameters than just changing the OAM value. Selective response to asymmetric helical light beams was […]
Solid electrolyte composed of nanoparticles shows promise for all-solid-state batteries
Phys.org October 2, 2024 Halide solid electrolytes are promising for improving the electrochemical performance of all-solid-state batteries. However, the state-of-the-art sodium-ion-conducting halides are not as high in conductivity as expected and lack reduction stability. Researchers in Japan found oxychlorides in a ternary system NaCl–TaCl5–Ta2O5 have high conductivities, formabilities, and oxidation and reduction stabilities. They mechanochemically prepared samples composed of NaCl and Ta2O5 nanoparticles embedded in an Na–Ta–Cl–O amorphous matrix, possessing ionic conductivities of 2.5 × 10–3 S cm–1 at 25 °C and electrochemical potential windows of 0.4–4.1 versus Na+/Na. Compression tests revealed that the nanoparticles in the oxychloride electrolytes improved […]
Why the gender gap in physics has been stable for more than a century
Phys.org September 26, 2024 Social and technical networks undergo constant evolution driven by both existing entities and newcomers. In academia, research papers are continually cited by new papers, while senior researchers integrate newly arrived junior researchers into their academic networks. Moreover, social systems can be influenced by external factors that could indirectly impact their growth patterns. For instance, systematic discrimination against certain groups in academia or managerial positions can impede their long-term growth, especially when combined with group-level preferences in hiring or adoption, as observed in our study. An international team of researchers (Germany, Austria) introduced a network growth and […]
Top 10 Science and Technology Inventions for the Week of September 27, 2024
01. First liquid-liquid extraction trial finds porous liquids can separate harmful or unwanted alcohols from mixtures 02. Light momentum turns pure silicon from an indirect to a direct bandgap semiconductor 03. New material with wavy layers of atoms exhibits unusual superconducting properties 04. Novel computational method addresses obstacles in phonon-based heat simulation 05. Physicists use quantum correlations of photon pairs to hide images from standard cameras 06. Researchers observe an antiferromagnetic diode effect in even-layered MnBi₂Te₄ 07. Thermal effects in spintronics systematically assessed for first time 08. High-pressure reactions can turn nonporous rocks into sponges 09. Engineers 3D print sturdy […]
Arctic warming may fuel ice formation in clouds, observations suggest
Phys.org September 19, 2024 The roles of Arctic aerosols as ice-nucleating particles are crucial for assessing the climate sensitivity of Arctic mixed-phase clouds and predicting their response to Arctic warming. An international team of researchers (Japan, Norway) presented a full-year record of ice-nucleating particle concentrations over Svalbard, where surface warming has been anomalously faster than the Arctic average. While the variation of ice-nucleating particles active at around −30 °C was relatively small, those active at higher temperatures tended to increase exponentially with rising surface air temperatures when the surface air temperatures rose above 0 °C and snow/ice-free barren and vegetated areas appeared […]