Phys.org September 22, 2024 Non-centrosymmetric polar conductors are intrinsic diodes that could be of use in the development of nonlinear applications. Such systems have recently been extended to non-centrosymmetric superconductors. An international team of researchers (USA – Harvard University, Northeastern University, MIT, UCLA, Boston College, Taiwan, India, Japan) has reported antiferromagnetic diode effect in a centrosymmetric crystal without directional charge separation. Large second-harmonic transport in a nonlinear electronic device enabled by the compensated antiferromagnetic state of even-layered MnBi2Te4. They showed that this antiferromagnetic diode effect could be used to create in-plane field-effect transistors and microwave-energy-harvesting devices, and electrical sum-frequency generation […]
Thermal effects in spintronics systematically assessed for first time
Phys.org September 24, 2024 Current-driven antiferromagnetic order switching has implications for next-generation spintronic devices. Some reports have claimed that demagnetization above the Néel temperature due to Joule heating is critical for switching. University of Illinois at Urbana-Champaign presented a systematic method and an analytical model to quantify the thermal contribution due to Joule heating in micro-electronic devices, focusing on current-driven octupole switching in the non-collinear antiferromagnet, Mn3Sn. Their results consistently showed that the critical temperature for switching remained relatively constant above the Néel temperature, while the threshold current density depended on the choice of substrate and the base temperature. They […]
Top 10 Science and Technology Inventions for the Week of September 20, 2024
01. Quantum researchers cause controlled ‘wobble’ in the nucleus of a single atom 02. New method improves understanding of light-wave propagation in anisotropic materials 03. Printing 3D photonic crystals that completely block light 04. Research team uses terahertz pulses of light to shed light on superconducting disorder 05. Generating spin currents directly using ultrashort laser pulses 06. Energy-saving computing with magnetic whirls 07. This screen stores and displays encrypted images without electronics 08. Why the next pandemic could come from the Arctic — and what to do about it 09. 2D silk protein layers on graphene pave the way for […]
2D silk protein layers on graphene pave the way for advanced microelectronics and computing
Phys.org September 18, 2024 A team of researchers in the US (Pacific Northwest National Laboratory, University of Washington, Lawrence Berkeley National Laboratory, North Carolina State University) developed highly ordered two-dimensional silk fibroin (SF) films grown epitaxially on van der Waals (vdW) substrates. They showed that the films consisted of lamellae of SF molecules that exhibited the same secondary structure as the nanocrystallites of native silk. Increasing the SF concentration resulted in multilayers that grew either by direct assembly of SF molecules into the lamellae or, at high concentrations, along a two-step pathway beginning with a disordered monolayer that crystallizes. They […]
Deep underground flooding beneath hot springs: A potential trigger for the 1995 Kobe earthquake
Phys.org September 13, 2024 In subduction zones, water expelled from the subducting slab is believed to be involved in seismic activity. However, little is known about its quantity and flow processes. Researchers in Japan showed that the Arima hot springs in western Japan contained high concentrations of water derived from the subducting Philippine Sea slab. A long-term record spanning over half a century revealed that the fraction of slab-derived water exhibited a temporary surge in the year preceding and/or subsequent years of the 1995 Kobe earthquake. In total, an estimated 2.6–4.2 × 105 cubic meters of slab-derived water was introduced in conjunction […]
Disappearing scientists: Attrition and retention patterns of 2.1 million scientists in 38 OECD countries
Phys.org September 16, 2024 An international team of researchers (Poland, Germany, USA – University of Colorado) explored how members of the scientific community leave academic science and how attrition (defined as ceasing to publish) differs across genders, academic disciplines, and over time. They tracked individual male and female scientists over time and quantified the phenomenon, using publication metadata from Scopus, following the details of the publishing careers of scientists from 38 OECD countries who started publishing in 2000 and 2010. The study was restricted to 16 STEMM disciplines (science, technology, engineering, mathematics, and medicine). They tracked the individual scholarly output […]
Energy-saving computing with magnetic whirls
Phys.org September 16, 2024 Magnetic skyrmions are promising candidates for reservoir computing systems due to their enhanced stability, non-linear interactions and low-power manipulation. Traditional spin-based reservoir computing has been limited to quasi-static detection or real-world data must be rescaled to the intrinsic timescale of the reservoir. An international team of researchers (Germany, The Netherlands, Norway) addressed this challenge by time-multiplexed skyrmion reservoir computing, that allowed for aligning the reservoir’s intrinsic timescales to real-world temporal patterns. Using millisecond-scale hand gestures recorded with Range-Doppler radar, they fed voltage excitations directly into their device and detected the skyrmion trajectory evolution. This method was […]
First flexible perovskite solar cells on polycarbonate films
Nanowerk September 14, 2024 Despite its widespread use in many applications, poor chemical resistance and roughness of polycarbonate (PC) has hindered its adoption as a substrate in solar cell technologies. An international team of researchers (Italy, Germany, Iran) developed a solution-processed planarizing layer using a commercial ambient-curable refractory resin through blade coating. Blade coating decreased film roughness from 1.46 µm to 23 nm, lowered water vapor transmission rates (WVTR) by a half, and significantly improved solvent resistance enabling deposition of precursor inks. The power conversion efficiency (PCE) reached 13.0%. The unencapsulated PSCs retained 80% of initial PCE after 1776 h […]
Floquet engineering tunes ultracold molecule interactions and produces two-axis twisting dynamics
Phys.org September 12, 2024 Polar molecules confined in an optical lattice are a versatile platform to explore spin-motion dynamics based on strong, long-range dipolar interactions. A team of researchers in the US (University of Colorado, Harvard University, industry) used Floquet engineering to realize new quantum many-body systems of polar molecules. Using a spin encoded in the two lowest rotational states of ultracold 40K87Rb molecules, they mutually validated XXZ spin models tuned by a Floquet microwave pulse sequence against those tuned by a d.c. electric field. This validation sets the stage for the realization of Hamiltonians inaccessible with static fields. They […]
Generating spin currents directly using ultrashort laser pulses
Phys.org September 13, 2024 An international team of researchers (USA – UC Berkeley, Lawrence Berkeley National Laboratory, France, Canada, Germany, Austria) measured the light-driven response of a magnetic multilayer structure made of thin alternating layers of cobalt and platinum at the few-femtosecond timescale. They observed how light rearranges the magnetic moment during and after excitation. The results revealed a sub-5 fs spike of magnetization in the platinum layer, which followed the shape of the driving pulse. They interpreted the observations as light-driven spin injection across the metallic layers of the structure. The light-triggered spin current was strikingly short, largely outpacing […]