Nanowerk April 24, 2024 Extensive efforts have been undertaken to combine superconductivity and the quantum Hall effect so that Cooper-pair transport between superconducting electrodes in Josephson junctions is mediated by one-dimensional edge states. So far it has proven challenging to achieve detectable supercurrents through quantum Hall conductors. An international team of researchers (UK, South Korea, Spain, Japan, USA – Yale University) showed that domain walls in minimally twisted bilayer graphene support exceptionally robust proximity superconductivity in the quantum Hall regime, allowing Josephson junctions to operate in fields close to the upper critical field of superconducting electrodes. The critical current was […]
Tag Archives: Materials science
Defect removal of 2D semiconductor crystals
Nanowerk April 11, 2024 The exact role of h-BN encapsulation in relation to the internal defects of 2D semiconductors in hexagonal boron nitride (h-BN) remains unclear. An international team of researchers (South Korea, Japan) reported that h-BN encapsulation greatly removes the defect-related gap states by stabilizing the chemisorbed oxygen molecules onto the defects of monolayer tungsten disulfide (WS2) crystals. Studies showed that h-BN encapsulation prevented the desorption of oxygen molecules over various excitation and ambient conditions, resulting in a greatly lowered and stabilized free electron density in monolayer WS2 crystals. This suppressed the exciton annihilation processes by two orders of […]
A universal path for converting light into current in solids
Phys.org April 16, 2024 Harnessing the asymmetric electronic population in the conduction band induced by an intense single-color circularly polarized laser pulse an international team of researchers (Japan, India, Germany) developed a universal method to generate ultrafast photocurrent in both inversion-symmetric and inversion-broken Weyl semimetals with degenerate Weyl nodes at the Fermi level. They found that the induced photocurrent could be tailored by manipulating helicity and ellipticity of the employed laser. Their approach generated photocurrent in realistic situations when the Weyl nodes were positioned at different energies and had finite tilt along a certain direction. According to the researchers their […]
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 […]
Bendable energy storage materials by cool science
Science Daily March 19, 2024 Mesoporous metal oxides exhibit excellent physicochemical properties and are widely used in various fields, including energy storage/conversion, catalysis, and sensors. Although several soft-template approaches are reported, high-temperature calcination for both metal oxide formation and template removal is necessary, which limits direct synthesis on a plastic substrate for flexible devices. Researchers in South Korea developed a universal synthetic approach that combines thermal activation and oxygen plasma to synthesize diverse mesoporous metal oxides (V2O5, V6O13, TiO2, Nb2O5, WO3, and MoO3) at low temperatures (150–200 °C), which could be applied to a flexible polymeric substrate. To demonstrate their […]
Researchers take major step toward developing next-generation solar cells
Science Daily March 22, 2024 The efficiency of p–i–n perovskite solar cells fabricated in air still lags behind those made in an inert atmosphere. An international team of researchers (China, USA-University of Colorado) introduced an ionic pair stabilizer, dimethylammonium formate (DMAFo), into the perovskite precursor solution to prevent the degradation of perovskite precursors. It inhibited the oxidization of iodide ions and deprotonation of organic cations, improved the crystallinity and reduced defects in the resulting perovskite films. They showed the generation of additional p-type defects during ambient air fabrication that suggested the need for improving bulk properties of the perovskite film […]
Supercomputer simulations of super-diamond suggest a path to its creation
Phys.org March 18, 2024 Despite several experimental attempts, synthesis, and recovery of the theoretically predicted post-diamond BC8 phase remains elusive. Through quantum-accurate multimillion atom molecular dynamics (MD) simulations, an international team of researchers (USA – University of South Florida, Los Alamos National Laboratory, Lawrence Livermore National Laboratory, Sweden) uncovered the extreme metastability of diamond at very high pressures, significantly exceeding its range of thermodynamic stability. They predicted the post-diamond BC8 phase to be experimentally accessible only within a narrow high pressure–temperature region of the carbon phase diagram. The diamond to BC8 transformation proceeded through premelting followed by BC8 nucleation and […]
Researchers find exception to 200-year-old scientific law governing heat transfer
Phys.org March 4, 2024 Researchers at UMass, Amherst, revisited the Fourier’s law for heat transfer and transport within translucent materials. They compared the model predictions to infrared-based measurements with nearly mK temperature resolution. After heat pulses, they found macroscale non-Gaussian tails in the surface temperature profile. At steady state, they found macroscale anomalous hot spots when the sample was topographically rough. These discrepancies from Fourier’s law for translucent materials suggested that internal radiation whose mean-free-path is millimeters interacted with defects to produce small heat sources that by secondary emission afford an additional, non-local mode of heat transport. According to the […]
Researchers create new compound to build space-age antennas
Science Daily February 29, 2024 Additive manufacturing with high-performance polymers can realize lightweight and complex geometries that can also be manufactured on board. However, polymers are electromagnetically inefficient for applications requiring electrical conductivity, such as guiding microwave signals. An international team of researchers (Canada, USA – Drexel University) developed MXene coated high-efficiency, lightweight additively manufactured microwave components with waveguiding functionality from 8 to 33 GHz, covering low earth orbit (LEO) frequencies, with a power-handling capability up to 10 dB and a transmission coefficient of 93 %. After a single dip-coating cycle, the polymer waveguide performed only 2 % below an […]
Zero-index metamaterials and the future
Phys.org March 6, 2024 Zero-index metamaterials (ZIMs) can support uniform electromagnetic field distributions at any frequency, but their applications are hampered by the ZIM’s homogenization level—only 3-unit cells per free-space wavelength, which is fundamentally limited by the low-permittivity inclusions and background matrix. An international team of researchers (USA – Stanford University, China) demonstrated a highly homogeneous microwave ZIM with an over threefold increase in the homogenization level by filling high-permittivity SrTiO3 ceramic pillars in BaTiO3 background matrix. They achieved an antenna, and a concave lens with a focal length of as short as 1λ0… read more. Open Access TECHNICAL ARTICLE