Forschung zu Covid-19

The discovery of superconductivity in a d^9−δ nickelate has inspired disparate theoretical perspectives regarding the essential physics of this class of materials. A key issue is the magnitude of the magnetic superexchange, which relates to whether cuprate-like high-temperature nickelate superconductivity could be realized. We address this question using Ni L-edge and O K-edge spectroscopy of the reduced d^9−1/3 trilayer nickelates R₄Ni₃O₈ (where R = La, Pr) and associated theoretical modeling.

Platinum chloride in aqueous solution promotes the dispersion of large gold nanoparticles (>70 nm) on carbon carriers into single atoms, forming bimetallic single-atom catalysts with improved resistance against sintering at temperatures up to 800 K and under the harsh reductive reaction conditions of acetylene hydrochlorination, leading to improved lifetime in this reaction. To rationalize these observations, this study, led by ETH Zurich, utilized X-ray adsorption spectroscopy conducted at the SuperXAS beamline of the SLS to provide insights into the degree of gold dispersion and the structure of the isolated metal sites in the bimetallic catalysts.

We have recently shown how a polarized beam in Talbot-Lau interferometric imaging can be used to analyze strong magnetic fields through the spin dependent differential phase effect at field gradients. While in that case an adiabatic spin coupling with the sample field is required, here we investigate a nonadiabatic coupling causing a spatial splitting of the neutron spin states with respect to the external magnetic field. This subsequently leads to no phase contrast signal but a loss of interferometer visibility referred to as dark-field contrast.

As exemplified by the growing interest in the quantum anomalous Hall effect, the research on topology as an organizing principle of quantum matter is greatly enriched from the interplay with magnetism. In this vein, we present a combined electrical and thermoelectrical transport study on the magnetic Weyl semimetal EuCd₂As₂. Unconventional contribution to the anomalous Hall and anomalous Nernst effects were observed both above and below the magnetic transition temperature of EuCd₂As₂, indicating the existence of significant Berry curvature.

The authors find using resonant and non-resonant x-ray diffraction on an x-ray free electron laser that the structural distortion and the underlying electronic structure of the charge density wave in TiSe₂ show different energetics at ultrafast timescales. This indicates that the lattice distortion stabilizes the charge density wave.

FEL-based ultrafast calorimetry measurements show enhancement and maximum in the isobaric specific-heat.

Scientists pioneer an approach called self-referenced streaking, clocking Auger electrons with sub-femtosecond resolution. The breakthrough will unlock the broader potential for attosecond time resolution at X-ray free-electron lasers.

The growing request for sophisticated electron beam manipulation techniques for the optimization of Free Electron Lasers (FELs) or novel acceleration techniques requires enhanced beam control capabilities  and characterization. One of the most important challenge is the development of new diagnostic techniques able to characterize the longitudinal phase space of the beam, including spatial correlation terms, with a resolution in the range of a few tens of fs to sub-fs.

In experiments at the Paul Scherrer Institute PSI, an international research collaboration has measured the radius of the atomic nucleus of helium five times more precisely than ever before. The researchers are publishing their results today in the journal Nature.