Research on Covid-19

We show that hybrid MnO_x/C₆₀ heterojunctions can be used to design a storage device for spin-polarized charge: a spin capacitor. Hybridization at the carbon-metal oxide interface leads to spin-polarized charge trapping after an applied voltage or photocurrent. Strong electronic structure changes, including a 1-eV energy shift and spin polarization in the C60 lowest unoccupied molecular orbital, are then revealed by x-ray absorption spectroscopy, in agreement with density functional theory simulations.

A collaboration of scientists from the ETH Zürich and the Paul Scherrer Institute successfully demonstrated the all-electric operation of a magnetic domain-wall based NAND logic gate, paving the way towards the development of logic applications beyond the conventional metal-oxide semiconductor technology. The work has been published in the journal Nature.

In this work, published on the front cover page of Advanced Materials, an international collaboration of Italian, American, and Swiss scientists demonstrated a novel concept for the generation and manipulation of spin waves, paving the way towards the development of magnonic nano-processors.

Can a skyrmion-based device be used to read a handwritten text? In this work, an international scientist collaboration led by the Korea Institute of Technology and the IBM Watson research center could provide a first answer to this question by fabricating a proof-of-principle single-neuron artificial neural network, using X-ray magnetic microscopy at the Swiss Light Source to investigate its performances.

Detailed understanding of charge diffusion processes in a lithium-ion battery is crucial to enable its systematic improvement. Experimental investigation of diffusion at the interface between active particles and the electrolyte is challenging but warrants investigation as it can introduce resistances that, for example, limit the charge and discharge rates. Here, we show an approach to study diffusion at interfaces using muon spin spectroscopy.

Spin-based logic architectures provide nonvolatile data retention, near-zero leakage, and scalability, extending the technology roadmap beyond complementary metal–oxide–semiconductor logic. Architectures based on magnetic domain walls take advantage of the fast motion, high density, non-volatility and flexible design of domain walls to process and store information. Such schemes, however, rely on domain-wall manipulation and clocking using an external magnetic field, which limits their implementation in dense, large-scale chips.

Topological properties of materials are of fundamental as well as practical importance. Of particular interest are unconven- tional superconductors that break time-reversal symmetry, for which the superconducting state is protected topologically and vortices can host Majorana fermions with potential use in quantum computing. However, in striking contrast to the unconventional A phase of superfluid ³He where chiral symmetry was directly observed, .....

We have produced hard x-ray free-electron laser (FEL) radiation with unprecedented large bandwidth tunable up to 2%. The experiments have been carried out at SwissFEL, the x-ray FEL facility at the Paul Scherrer Institute in Switzerland. The bandwidth is enhanced by maximizing the energy chirp of the electron beam, which is accomplished by optimizing the compression setup. We demonstrate continuous tunability of the bandwidth with a simple method only requiring a quadrupole magnet. The generation of such broadband FEL pulses will improve the efficiency of many techniques such as x-ray crystallography and spectroscopy, opening the door to significant progress in photon science. It has already been demonstrated that the broadband pulses of SwissFEL are beneficial to enhance the performance of crystallography, and further SwissFEL users plan to exploit this large bandwidth radiation to improve the efficiency of their measurement techniques.

Unlike the homogeneous Wacker process, the understanding of the mechanism of the heterogeneous system has long remained to be superficial. Here the authors investigated the mechanism of heterogeneous Wacker oxidation over Pd-Cu/zeolite Y through transient XAS coupled with kinetic studies and chemometric analysis.

Small and narrowly distributed nanoparticles of copper alloyed with gallium supported on silica containing residual Ga^III sites can be obtained via surface organometallic chemistry. This material is highly active and selective for CO₂ hydrogenation to CH₃OH. In situ X-ray absorption spectroscopy shows that gallium is oxidized under reaction conditions while copper remains as Cu⁰.

When magnetism meets topology, colorful novel states can emerge in condensed matter. It is widely believed that parity-time symmetry plays an essential role for the formation of Dirac states in Dirac semimetals. So far, all of the experimentally identified topological nontrivial Dirac semimetals possess both parity and time reversal symmetry. Since the magnetism will break time-reversal symmetry, only in special cases the Dirac states can be protected in a magnetic system. Thus, the realization of magnetic topological Dirac materials remains a major issue in the research of topological physics. In this work, the authors ascertained that the ground state of EuCd₂As₂ is a good candidate for magnetic topological Dirac semimetal when the spins point in the out-of-plane direction in the A-type antiferromagnetic phase. The Dirac state is protected by the combination of parity-time symmetry with additional translation operation. Moreover, when the spins deviate from out-of-plane direction, the bulk Dirac cone will open a gap, and the system develops into a novel state containing axion insulator, antiferromagnetic topological crystalline insulator, and higher order topological insulator.

When magnetism meets topology, colorful novel states can emerge in condensed matter. It is widely believed that parity-time symmetry plays an essential role for the formation of Dirac states in Dirac semimetals. So far, all of the experimentally identified topological nontrivial Dirac semimetals possess both parity and time reversal symmetry. Since the magnetism will break time-reversal symmetry, only in special cases the Dirac states can be protected in a magnetic system. Thus, the realization of magnetic topological Dirac materials remains a major issue in the research of topological physics. In this work, the authors ascertained that the ground state of EuCd₂As₂ is a good candidate for magnetic topological Dirac semimetal when the spins point in the out-of-plane direction in the A-type antiferromagnetic phase. The Dirac state is protected by the combination of parity-time symmetry with additional translation operation. Moreover, when the spins deviate from out-of-plane direction, the bulk Dirac cone will open a gap, and the system develops into a novel state containing axion insulator, antiferromagnetic topological crystalline insulator, and higher order topological insulator.

Employing a tailored multilayered magnetic film, optimized for the zero-field stabilization of magnetic skyrmions, researchers have investigated the influence of the skyrmion diameter on its current-induced sideways motion, uncovering mechanisms that allow for this topological property to be controlled.

The Innovation Award on Synchrotron Radiation 2019 was given to the researchers Prof. Heinz Graafsma from Desy and Dr. Aldo Mozzanica and Dr. Bernd Schmitt both from the Paul Scherrer Institute. The three physicists were honored for their contributions to the development of detectors for XFEL applications based on the dynamic gain switching principle enabling simultaneously single photon resolution and a large dynamic range. The laudation was held by Prof. Edgar Weckert from Desy. The Synchrotron Radiation Innovation Award is sponsored by SPECS GmbH and BESTEC GmbH.

The grating fabrication team of the X-ray tomography group has scored another record in etching technology of silicon by realizing a MacEtch process in gas phase. Ultra-high aspect ratios (up to 10 000 : 1) in the nanoscale regime (down to 10 nm) were achieved by platinum assisted chemical etching of silicon in the gas phase. The results were published in Nanoscale Horizons on February 17, 2020.

We report a comprehensive muon spin rotation (μSR) study of the prototypical magnetoelectric antiferromagnet Cr₂O₃. We find the positively charged muon (μ⁺) occupies several distinct interstitial sites and displays a rich dynamic behavior involving local hopping, thermally activated site transitions, and the formation of a charge-neutral complex composed of a muon and an electron polaron.