Phys.org March 18, 2024 Researchers at Carnegie Mellon University designed a thermal photonic nanodevice for the first measurement of near-field energy transport between two coplanar subwavelength structures over temperature bias up to ∼190 K. Their experimental results demonstrated a 20-fold enhancement in energy transfer beyond blackbody radiation. In contrast with the well-established near-field interactions between two semi-infinite bodies, the subwavelength confinements in nanodevices led to increased polariton scattering and reduction of supporting photonic modes and, therefore, a lower energy flow at a given separation. According to the researchers their work opens new designs for nanodevices, particularly for coplanar near-field energy […]
Author Archives: Hema Viswanath
High-quality microwave signals generated from tiny photonic chip
Nanowerk March 19, 2024 Current implementations of optical frequency division (OFD) require multiple lasers, with space- and energy-consuming optical stabilization and electronic feedback components, resulting in device footprints incompatible with integration into a compact and robust photonic platform. A team of researchers in the US (industry, Columbia University) demonstrated all-optical OFD on a photonic chip by synchronizing two distinct dynamical states of Kerr microresonators pumped by a single continuous-wave laser. The inherent stability of the terahertz beat frequency was transferred to a microwave frequency of a Kerr soliton comb, and synchronized via a coupling waveguide without the need for electronic […]
Holographic message encoded in simple plastic
Phys.org March 18, 2024 Researchers in Austria produced a sub-terahertz holographic image of a two-dimensional 576-bit data code using a diffractive phase-plate element. The phase plate was designed to encode a focused image of the data code into a phase modulation profile. The complex phase plate structure is fabricated from polylactic acid using fused deposition modeling, a common three-dimensional-printing technique. The simplified optical setup, consisted of a 0.14 THz diverging source, the holographic phase plate, and a scanning detector, without the need for additional optical elements. The information stored in the data code was an example of a cryptographic private […]
New method enables synthesis of hundreds of new 2D materials
Phys.org March 14, 2024 MXenes are a family of 2D materials typically formed by etching the A element from a parent MAX phase. Computational screening for other 3D precursors suitable for such exfoliation is challenging because of the intricate chemical processes involved. Researchers in Sweden proposed a theoretical approach for predicting 2D materials formed through chemical exfoliation under acidic conditions by identifying 3D materials amenable for selective etching. From a dataset of 66,643 3D materials, they identified 119 potentially exfoliable candidates, within several materials families. To corroborate the method, they chose a material distinctly different from MAX phases, in terms […]
Photon-like electrons in a four-dimensional world discovered in a real material
Phys.org March 14, 2024 Because of their differences from standard electrons, Dirac electrons are expected to add unprecedented electronic properties to materials. Researchers in Japan discovered a method enabling selective observation of the Dirac electrons in materials. Using electron spin resonance, to directly observe unpaired electrons in materials to distinguish differences in character, they established a method to determine their scope of action in the materials and their energies. They showed that electron spin resonance revealed that α-ET2I3 (ET = bis(ethylenedithio)-tetrathiafulvalene) at 1 bar contained a nearly three-dimensional DFs above ∼100 K coexisting with standard fermions. The close charge-transfer ET–I3 […]
Projection mapping leaves the darkness behind
Phys.org March 18, 2024 Projection mapping (PM) typically requires a dark environment to achieve high-quality projections, limiting its practicality. Researchers in Japan overcame this limitation by replacing conventional room lighting with heterogeneous projectors. These projectors replicated environmental lighting by selectively illuminating the scene, excluding the projection target. They developed distributed projector optimization framework designed to effectively replicate environmental lighting and incorporated a large-aperture projector, in addition to standard projectors, to reduce high-luminance emitted rays and hard shadows. To validate their approach, they conducted a series of quantitative and qualitative experiments. They successfully demonstrated that their projector-based lighting system significantly enhanced […]
Quantum dance to the beat of a drum: Researchers observe how energy of single electron is tuned by surrounding atoms
Phys.org March 14, 2024 Direct observation of the relevant interplay of the electronic structure of a single defect with other microscopic elementary excitations on their intrinsic length, time and energy scales has not been achieved. Researchers in Germany directly resolved in space, time, and energy how a spin–orbit-split energy level of an isolated selenium vacancy in a moiré-distorted WSe2 monolayer evolved under the controlled excitation of lattice vibrations. By locally launching a phonon oscillation and taking ultrafast energy-resolved snapshots of the vacancy’s states faster than the vibration period, they directly measured the impact of electron–phonon coupling in an isolated single-atom […]
Researchers achieve >99% photoluminescence quantum yield in metal nanoclusters
Phys.org March 18, 2024 Metal nanoclusters have emerged as NIR–emissive materials, but their room-temperature photoluminescence quantum yield (PLQY), especially in solution, is often low. Researchers in China studied the photophysics of Au22(tBuPhC≡C)18 (Au22) and its alloy counterpart Au16Cu6(tBuPhC≡C)18 (Au16Cu6) (where tBu is tert-butyl and Ph is phenyl) and found that copper doping suppressed the nonradiative decay and promoted intersystem crossing rate ~300-fold higher. According to the researchers their approach could enable the development of highly emissive metal cluster materials… read more. TECHNICAL ARTICLE
Researchers develop novel ‘super-tetragonal’ sacrificial layer for freestanding oxide membranes
Phys.org March 18, 2024 Freestanding oxide membranes have a variety of interesting applications, but pulling these materials off the substrate after synthesis can be challenging. An international team of researchers (China, Austria) has developed a water-soluble sacrificial layer, “super-tetragonal” Sr4Al2O7 (SAOT). The low-symmetric crystal structure enabled a superior capability to sustain epitaxial strain, allowing for broad tunability in lattice constants resulting in structural coherency and defect-free interface in perovskite ABO3/SAOT heterostructures effectively restraining crack formation during the water release of freestanding oxide membranes. For a variety of nonferroelectric oxide membranes, the crack-free areas can span up to a millimeter in […]
Researchers discover new yttrium-hydrogen compounds with implications for high-pressure superconductivity
Phys.org March 14, 2024 An international team of researchers (Germany, UK, USA – University of Chicago) used synchrotron single-crystal x-ray diffraction (SCXRD) and found (two YH3 phases) and five previously unknown yttrium hydrides. These were synthesized in diamond anvil cells by laser heating yttrium with hydrogen-rich precursors—ammonia borane or paraffin oil. The arrangements of yttrium atoms in the crystal structures of new phases were determined based on SCXRD, and the hydrogen content estimations based on empirical relations and ab initio calculations revealed the following compounds: Y3H11, Y2H9, Y4H23, Y13H75, and Y4H25. They also uncovered a carbide and two yttrium allotropes. […]