Phys.org October 22, 2024 Memristors based on graphene is a promising alternative to contemporary field-effect transistor (FET) technology achieves higher integration density and lower power consumption. The use of graphene as electrodes in memristors could also increase robustness against degradation mechanisms. To realize this researchers in the UK have developed a process for direct growth of high-quality monolayer graphene on sapphire wafers in a mass-producible, contamination-free, and transfer-free manner using a commercially available metal–organic chemical vapor deposition (MOCVD) system. Using their process they developed graphene-electrode based memristors incorporating graphene electrodes at wafer scale. The memristor demonstrated promising characteristics in terms […]
Magnetic octupoles help overcome problems with antiferromagnets
Phys.org October 17, 2024 The insensitive magneto-electric responses of antiferromagnets (AFMs) make controlling them in domain-wall devices challenging. An international team of researchers (Japan, USA – UCLA) demonstrated a current-driven fast magnetic octupole domain-wall (MODW) motion in Mn3X. The magneto-optical Kerr observation showed that the Néel-like MODW of Mn3Ge could be accelerated up to 750 m s-1 with a current density of only 7.56 × 1010 A m-2 without external magnetic fields. The MODWs showed high mobility with a small critical current density. They theoretically extended the spin-torque phenomenology for domain-wall dynamics from collinear to noncollinear magnetic systems. According to the researchers […]
A multi-level breakthrough in optical computing—a faster, more efficient, and robust memory cell
Phys.org October 23, 2024 A typical approach to photonic processing is to multiply a rapidly changing optical input vector with a matrix of fixed optical weights. However, encoding these weights on-chip using an array of photonic memory cells is currently limited by a wide range of material- and device-level issues, such as the programming speed, extinction ratio and endurance, among others. An international team of researchers (USA – UC Santa Barbara, University of Pittsburg, Italy, Japan) proposed a new approach to encoding optical weights for in-memory photonic computing using magneto-optic memory cells comprising heterogeneously integrated cerium-substituted yttrium iron garnet (Ce:YIG) […]
New electrochemical water splitting method offers fast, sustainable method for hydrogen production
Phys.org October 21, 2024 One of the biggest challenges in electrochemical water splitting is oxygen evolution reaction (OER), a sluggish reaction in which water molecules are broken down into oxygen and hydrogen. The OER can be accelerated by using noble metal catalysts; however, these metals are expensive and scarce, and speeding up the reaction requires additional energy. An international team of researchers (USA – Perdue University, China, Taiwan, Germany) has developed a new method using iridium coordinated with dimethylimidazole (MI) as a reaction accelerator for electrochemical splitting of water which accelerated the production of hydrogen and made it more sustainable. […]
New ice core data provide insight into climate ‘tipping points’ during the last Ice Age
Phys.org October 22, 2024 Reconstructions of Earth’s past climate show evidence for instability and abrupt change, which are of great scientific and societal importance. The Dansgaard–Oeschger (DO) oscillation of the last Ice Age, which is most clearly observed in Greenland ice cores, is the prime example of such instability. An international team of researchers (Oregon State University, Pennsylvania State University, University of Miami, University of Colorado, Denmark, UK) presented ice-core records from south and coastal east Greenland to calibrate the local water isotope thermometer and provided a Greenland-wide spatial characterization of DO event magnitude. They used a series of idealized […]
Researchers reveal quantum advantage that could advance future sensing devices
Phys.org October 16, 2024 Quantum metrology takes advantage of quantum correlations to enhance the sensitivity of sensors and measurement techniques beyond their fundamental classical limit. The use of both temporal and spatial correlations present in quantum states of light can extend quantum-enhanced sensing to a parallel configuration that can simultaneously probe an array of sensors or independently measure multiple parameters. Researchers at the University of Oklahoma used multispatial-mode bright twin beams of light to probe a four-sensor quadrant plasmonic array. They showed that it is possible to independently and simultaneously measure local changes in refractive index for all four sensors […]
Silicon metasurfaces unlock broad-spectrum infrared imaging
Phys.org October 16, 2024 Nonlinear metasurfaces are used for infrared imaging and spectroscopy. However, due to their low conversion efficiencies several strategies have been adopted to enhance their performances. Using resonances at signal or nonlinear emission wavelengths results in a narrow operational band of the nonlinear metasurfaces, which has bottlenecked many applications, including nonlinear holography, image encoding, and nonlinear metalenses. An international team of researchers (UK, Australia) introduced a new nonlinear imaging platform to overcome this issue. They demonstrated broadband nonlinear imaging for arbitrary objects using metasurfaces. A silicon disk-on-slab metasurface was introduced with an excitable guided-mode resonance at the […]
Study: Smaller, more specific academic journals hold more sway over conservation policy
Phys.org October 17, 2024 Academic review, promotion, and tenure processes place a premium on frequent publication in high-impact factor (IF) journals. However, conservation often relies on species-specific information that is unlikely to have the broad appeal needed for high-IF journals. Instead, this information is often distributed in low-IF, taxa- and region-specific journals. To explore mismatch between the incentives for academic researchers and the scientific needs of conservation implementation researchers at Duke University looked at federal implementation of the ESA. Most of the peer-reviewed academic articles referenced in ESA listings came from low-IF or no-IF journals that tended to focus on […]
Superconductivity offers new insights into quantum material MnBiâ‚‚Teâ‚„
Phys.org October 23, 2024 Topological superconductors hosting Majorana zero modes are of great interest for both fundamental physics and potential quantum computing applications. Researchers in the Netherlands investigated the transport properties of the intrinsic magnetic topological insulator MnBi2Te4 (MBT). They found that the presence of chiral edge channels, though with deviations from perfect quantization due to factors such as non-uniform thickness, domain structures, and the presence of quasi-helical edge states. The fabricated superconducting junctions using niobium led on MBT exfoliated flakes, which showed an onset of supercurrent with clear Josephson coupling. The interference patterns in the superconducting junctions revealed interesting […]
Towards better solar cells: Exploring an anomalous phenomenon of electricity generation
Phys.org October 22, 2024 The photovoltaic effect can occur without metal/semiconductor or semiconductor/semiconductor interfaces in materials with spontaneous electric polarization due to a lack of spatial inversion symmetry known as bulk photovoltaic (BPV) effect which facilitates photoelectric conversion. Researchers in Japan reported an experimental demonstration of the BPV effect in α-In2Se3 films along the out-of-plane direction by using graphite films as transparent electrodes. A short-circuit current was detected under white light irradiation, and the sign was inverted upon inverting the direction of electric polarization, thus suggesting its origin to be the shift current, distinct from the effect occurring at the […]