Scientific Highlights

The TOMCAT beamline at the Swiss Light Source specializes in rapid high-resolution 3-dimensional tomographic microscopy measurements with a strong focus on biomedical imaging. The team has recently developed a technique to acquire micrometer-scale resolution datasets on the entire lung structure of a juvenile rat in its fresh natural state within the animal’s body and without the need for any fixation, staining or other alteration that would affect the observed structure (E. Borisova et al., 2020, Histochem Cell Biol).

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.

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 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.

3D imaging using synchrotron radiation is a widely used tool that allows access to the inner structure of complex objects. An international and interdisciplinary consortium of scientists from the Swiss Light Source (PolLux and cSAXs), the Friedrich-Alexander-Universität Erlangen-Nürnberg, and the University of Cambridge developed the new 3D imaging technique of Soft X-ray Laminography (SoXL). SoXL allows for the investigation of thin and extended samples while taking advantage of the characteristic absorption contrast mechanisms in the soft X-ray range, providing 3D information with nm spatial resolution.

Detailed characterization of cellular structure and development of exceptionally preserved ancient tiny fossils from South China by synchrotron based X-ray tomographic microscopy at TOMCAT led an international team of researchers from the University of Bristol and Nanjing Institute of Geology and Palaeontology to the discovery that animal-like embryos evolved long before the first animals appear in the fossil record.

Researchers of the Paul Scherrer Institut have previously generated 3-D images of a commercially available computer chip. This was achieved using a high-resolution tomography method. Now they extended their imaging approach to a so-called laminography geometry to remove the requirement of preparing isolated samples, also enabling imaging at various magnification. For ptychographic X-ray laminography (PyXL) a new instrument was developed and built, and new data reconstruction algorithms were implemented to align the projections and reconstruct a 3D dataset. The new capabilities were demonstrated by imaging a 16 nm FinFET integrated circuit at 18.9 nm 3D resolution at the Swiss Light Source. The results are reported in the latest edition of the journal Nature Electronics. The imaging technique is not limited to integrated circuits, but can be used for high-resolution 3D imaging of flat extended samples. Thus the researchers start now to exploit other areas of science ranging from biology to magnetism.

Quantum materials that feature magnetic long-range order often reveal complex phase diagrams when localized electrons become mobile. In many materials magnetism is rapidly suppressed as electronic charges dissolve into the conduction band. In materials where magnetism persists, it is unclear how the magnetic properties are affected. 

Researchers from the Helmholtz Zentrum Berlin (HZB) and the TOMCAT beamline have achieved a new world record in time-resolved tomography by measuring over 200 tomographies per second during heating of an evolving aluminium metal foam.

The increasingly popular power-to-gas technology for the utilization of hydrogen as a clean energy vector involves the use of electrolyzers to convert water into H₂ and O₂. The oxygen evolution reaction (OER) is the least efficient among these processes, and a catalyst is required to speed up its kinetics at the high potentials (customarily ≥ 1.4 V vs. the reversible hydrogen electrode) at which the reaction takes place. 

Weyl fermions as emergent quasiparticles can arise in Weyl semimetals (WSMs) in which the energy bands are nondegenerate, resulting from inversion or time-reversal symmetry breaking. Nevertheless, experimental evidence for magnetically induced WSMs is scarce. Here, using photoemission spectroscopy, we observe that the degeneracy of Bloch bands is already lifted in the paramagnetic phase of EuCd₂As₂. We attribute this effect to the itinerant electrons experiencing quasi-static and quasi–long-range ferromagnetic fluctuations.

From 17 – 21 June 2019 the Neutron and Muon Division (NUM) and the Photon Science Division (PSD) of PSI hosted 18 Master Degree students of physics, chemistry, materials and interdisciplinary science, as well as nuclear engineering to provide an introduction to the characterization of materials with large scale facilities like SINQ, SμS, SLS and SwissFEL. The course taught a basic understanding of how photons, neutrons and muons interact with matter, and how this knowledge can be used to solve specific problems in materials research.

Details of the program can be found at http://indico.psi.ch/event/PSImasterschool

Lithography‐like writing of conducting regions at the interface between SrTiO₃ and amorphous Si using X‐ray irradiation opens ways for spatially controlled functionalities in oxide heterostructures.

In the week of April 1-5 PSI welcomes 20 PhD students and postdocs taking part in the European HERCULES 2019 school on Neutron and Synchrotron Radiation. They will attend lectures and perform two days of practical courses at several beam lines of the Swiss Light Source.

Lithium ion batteries (LIB) are essential in modern everyday life, with increasing interest in enhancing their performance and lifetime. Secondary particles of Li-rich cathode material were examined with correlated ptychographic X-ray tomography and diffraction microscopy at different stages of cycling to probe the aging mechanism.

Niéli’s paper is accepted in the Journal of Physical Chemistry Letters! We use X-ray absorption spectroscopy and X-ray magnetic circular dichroism to watch directly how the Co and Fe ions in a molecular cube change their oxidation states and turn from diamagnetic into paramagnetic units upon light irradiation.

Additive manufacturing of high-entropy alloys combines the mechanical properties of this novel family of alloys with the geometrical freedom and complexity required by modern designs. An approach to additive manufacturing of high-entropy alloys has been developed based on 3D extrusion of inks containing a blend of oxide nanopowders (Co₃O₄ + Cr₂O₃ + Fe₂O₃ + NiO), followed by co-reduction to metals, inter-diffusion and sintering to near-full density CoCrFeNi in H₂. A complex phase evolution path is observed by in-situ X-ray diffraction in extruded filaments: the oxide phases undergo reduction and the resulting metals inter-diffuse, ultimately forming the desired fcc-CoCrFeNi alloy (see figure). Linked to this phase evolution is a complex micro-structural one, from loosely packed oxide particles to fully-annealed, metallic CoCrFeNi with 99.6 ± 0.1% relative density. CoCrFeNi micro-lattices are created with strut diameters as low as 100 μm and excellent mechanical properties at ambient and cryogenic temperatures.

Abdominal aortic aneurysm, an enlargement of the abdominal aorta, may lead to rupture and thus acute health issues and death. Scanning X-ray imaging enabled new insights in the nano-structure of calcifications associated with abdonimal and popliteal aneurysm and allowed mapping the distribution of nano- and micro-calcifications as well as of collagen, elastin and myofilament as building blocks of connective tissue across samples from human donors.

Scientists have demonstrated in a combined theoretical and experimental effort that the new ligand-field density functional theory method (LF-DFT) can be used to calculate the X-ray absorption spectra (XAS) and X-ray magnetic circular dichroism (XMCD) of lanthanide compounds from purely structural input.

Synchrotron-based X-ray tomographic microscopy of melanophores (skin pigment cells) of an amazingly well preserved 180 million years old ichtyosaur (extinct marine reptile similar to whales) contributed in a multidisciplinary investigation to the new findings published today in Nature.

The reliable electrical detection of magnetic skyrmions is of fundamental importance for the application of such topological magnetic quasi-particles for data storage devices. Researchers in a joint collaboration between the University of Leeds and the PolLux endstation have investigated the electrical detection of isolated magnetic skyrmions in applications-relevant nanostructured devices, observing the presence of a strong skyrmion-dependent contribution to the Hall resistivity.