Recherche sur le Covid-19

Intertwining quantum order and non-trivial topology is at the frontier of condensed matter physics. A charge- density-wave-like order with orbital currents has been pro- posed for achieving the quantum anomalous Hall effect in topological materials and for the hidden phase in cuprate high-temperature superconductors. However, the experimental realization of such an order is challenging. Here we use high-resolution scanning tunnelling microscopy to discover an unconventional chiral charge order in a kagome material, KV₃Sb₅, with both a topological band structure and a superconducting ground state.

An article on the on-demand sample delivery and protein crystallography using acoustic levitation has been selected in an Applied Physics Letters collection of papers on technology and application of acoustic tweezers.

Encapsulation of highly dispersed palladium oxide clusters in the microporous channels and voids of the nanosized silicalite-1 crystals has been achieved by using an amine-based ligand.

The possibility of tuning the magnetic properties of materials with voltage (converse magnetoelectricity) or generating electric voltage with magnetic fields (direct magnetoelectricity) has opened new avenues in a large variety of technological fields, ranging from information technologies to healthcare devices and including a great number of multifunctional integrated systems, such as mechanical antennas, magnetometers, and radio frequency (RF) tunable inductors, which have been realized due to the strong strain-mediated magnetoelectric (ME) coupling found in ME composites. The development of single-phase multiferroic materials (which exhibit simultaneous ferroelectric and ferromagnetic or antiferromagnetic orders), multiferroic heterostructures, as well as progress in other ME mechanisms, such as electrostatic surface charging or magneto-ionics (voltage-driven ion migration), have a large potential to boost energy efficiency in spintronics and magnetic actuators. This article focuses on existing ME materials and devices and reviews the state of the art in their performance.

The silver ruthenium oxide AgRuO₃ consists of honeycomb Ru₂⁵⁺O₆²⁻ layers and can be considered and can be considered an analogue of SrRu₂O₆ with a different intercalation. We present measurements of magnetic susceptibility and specific heat on AgRuO₃ single crystals, which reveal a sharp antiferromagnetic transition at 342(3) K. The electrical transport in single crystals of AgRuO₃ is determined by a combination of activated conduction over an intrinsic semiconducting gap of ≈100 meV and carriers trapped and thermally released from defects.

In a study published in Nature Communications, researchers at the NHC Key Laboratory of Systems Biology of Pathogens in Beijing, China, in collaboration with the Paul Scherrer Institut characterize the interactions of SARS-CoV-2 orf9b and human TOM70 biochemically, and they determine the 2.2 Å crystal structure of the TOM70 cytosolic domain with a bound SARS-CoV-2 orf9b peptide.

Researchers from the University of Oxford, the Diamond Light Source and the Paul Scherrer Institut have generated strong evidence supporting one of two competing theories regarding the mechanism by which lithium metal dendrites grow through ceramic electrolytes. A process leading to short circuit at high rates of charge. The X-ray phase-contrast imaging capabilities of the TOMCAT beamline of the Swiss light source allowed researchers to visualize and characterize the growth of cracks and dendrites deep within an operating solid-state battery. The results were published in Nature Materials on April 22, 2021.

Various imaging methods in materials research have pursued the characterization of material composition and its change in space and time. When it comes to liquid matter far from equilibrium, such as mixing and evaporating mixtures of solutes and solvents, of paramount importance in diverse solution-processing methods, the quantitative and in situ characterization remains challenging. Our research with the evaporating ...

The step-wise oxidation of a new redox-active molecular semiconductor is recognized by changing shape, assembly behavior and other properties by spectro-microscopy correlation.  

Myelin 'insulates' our neurons enabling fast signal transduction in our brain. Myelin levels, integrity, and neuron orientations are important determinants of brain development and disease. Small-angle X-ray scattering tensor tomography (SAXS-TT) is a promising technique for non-destructive, stain-free imaging of brain samples, enabling quantitative studies of myelination and neuron orientations, i.e. of nano-scale properties imaged over centimeter-sized samples.

Ultrafast manipulation of magnetic states holds great promise for progress in our understanding of new quantum states and technical applications, but our current knowledge of transient magnetism is very limited. Our work elucidates the nature of transient magnetism in gapped antiferromagnets using Sr₃Ir₂O₇ as a model material. We find that transient magnetic fluctuations are trapped throughout the entire Brillouin zone while remaining present beyond the time that is required to restore the original spin network.

The exploration of topological electronic phases that result from strong electronic correlations is a frontier in condensed matter physics. One class of systems that is currently emerging as a platform for such studies are so-called kagome magnets based on transition metals. Using muon spin-rotation, we explore magnetic correlations in the kagome magnet Co₃Sn_2−xIn_xS₂ as a function of In-doping, providing putative evidence for an intriguing incommensurate helimagnetic (HM) state. Our results show that, while the undoped sample exhibits an out-of-plane ferromagnetic (FM) ground state, at 5% of In-doping the system enters a state in which FM and in-plane antiferromagnetic (AFM) phases coexist.

In a study addressing the global health threat of drug resistance, researchers at the Biozentrum, University of Basel, have revealed how a new antibiotic, Darobactin, binds to the external membrane of gram-negative bacteria.

We present x-ray ptychographic topography, a method for strain imaging, and demonstrate its use on an InSb micropillar after microcompression, where the strained region is visualized with a spatial resolution of 30 nm.