PSI hosted again the Hercules School in March 2022. We had the pleasure to welcome 20 international PhD students, PostDocs and scientists to demonstrate our state-of-the-art techniques and methodologies at our large scale facilities, the Swiss Light Source (SLS), the Swiss Spallation Neutron Source (SINQ) and our free electron laser SwissFEL.
Topological semimetals are three dimensional materials with symmetry-protected massless bulk excitations. As a special case, Weyl nodal-line semimetals are realized in materials having either no inversion or broken time-reversal symmetry and feature bulk nodal lines. The 111-family, including LaNiSi, LaPtSi and LaPtGe materials (all lacking inversion symmetry), belongs to this class. Here, by combining muon-spin rotation and relaxation with thermodynamic measurements, we find that these materials exhibit a fully- gapped superconducting ground state, while spontaneously breaking time-reversal symmetry at the superconducting transition.
Recent observations of novel spin-orbit coupled states have generated interest in 4d/5d transition metal systems. A prime example is the Jeff = 1/2 state in iridate materials and α-RuCl that drives Kitaev interactions. Here, by tuning the competition between spin-orbit interaction (λSOC) and trigonal crystal field (ΔT), we restructure the spin-orbital wave functions into a previously unobserved μ=1/2 state that drives Ising interactions.
We present a new measurement of the bottom quark mass in the MS scheme at the renormalization scale of the Higgs boson mass from measurements of Higgs boson decay rates at the LHC: mb (mH) = 2.6 +0.36-0.31 GeV. The measurement has a negligible theory uncertainty and excellent prospects to improve at the HL-LHC and a future Higgs factory.
Scientists, publishing in Nature, have found that a hybrid antimatter-matter atom behaves in an unexpected way when submerged in superfluid helium.
Spin glasses, generally defined as disordered systems with randomized competing interactions, are a widely investigated complex system. Theoretical models describing spin glasses are broadly used in other complex systems, such as those describing brain function, error-correcting codes or stock-market dynamics. This wide interest in spin glasses provides strong motivation to generate an artificial spin glass within the framework of artificial spin ice systems. Here we present the experimental realization of an artificial spin glass consisting of dipolar coupled single-domain Ising-type nanomagnets arranged onto an interaction network that replicates the aspects of a Hopfield neural network.
Macroscopic mapping of microscale fibers in freeform injection molded fiber-reinforced composites using X-ray scattering tensor tomography
Prediction of the mechanical properties dictated by the local microfiber orientation is essential for the performance characterization of fiber-reinforced composites. Typically, tomographic imaging methods that provide fine spatial resolution are employed to investigate various materials' local micro- and nano-architecture in a non-destructive manner. However, conventional imaging techniques are limited by a substantial trade-off between the structure size of interest and the accessible field of view (FOV). Researchers from the TOMCAT beamline at Paul Scherrer Institut, Xnovo Technology ApS, and the Technical University of Denmark have demonstrated the potential of X-ray scattering tensor tomography for industrial applications by characterizing the microstructure of a centimeter-sized industrially relevant freeform injection molding fiber-reinforced composite sample. This emerging technique provides unprecedented access to microstructural information over centimeter-sized sample volumes paving the way towards its potential integration as an invaluable tool, for instance, in the fiber-reinforced-composite (FRC) industry. The obtained fiber orientation and anisotropy information over statistically relevant large volumes can be used to predict the mechanical properties of final products, optimize production parameters, and improve fiber injection molding simulation frameworks. The work is published in Composites Part B: Engineering on 15 March 2022.
The conversion efficiency for green hydrogen production in a polymer electrolyte water electrolyzer (PEWE) is strongly influenced by the ohmic cell resistance and therefore the thickness of the membrane used. The use of thin membranes (~50 micron or below) is limited by gas crossover of H2 and O2, which can lead to the formation of explosive gas mixtures. The incorporation of a recombination catalyst provides remedy and allows a more dynamic operating mode.
In contrast to circular dichroism that is dependent on the polarization, helicoidal dichroism induced by a twisted wave front profile is scarcely known. The first evidence of magnetic helicoidal dichroism has now been observed in an experiment using Spiral Fresnel Zone Plates developed at the Paul Scherrer Institut.
A novel approach to controlling the speed of magnetic processes has been found through resonant magnetic scattering in an antiferromagnetic Lanthanide intermetallics.