Conventional superconductivity in the doped kagome superconductor Cs(V0.86Ta0.14)3Sb5 from vortex lattice studies
A hallmark of unconventional superconductors is a complex electronic phase diagram where intertwined orders of charge-spin-lattice degrees of freedom compete and coexist. While the kagome metals such as CsV3Sb5 also exhibit complex behavior, involving coexisting charge density wave order and superconductivity, much is unclear about the microscopic origin of the superconducting pairing. We study the vortex lattice in the superconducting state of Cs(V0.86Ta0.14)3Sb5, where the Ta-doping suppresses charge order and enhances superconductivity. Using small-angle neutron scattering ...
Nanoimaging Reveals Topological Textures in Nanoscale Crystalline Networks
X-ray nano-tomography reveals collective behavior in synthetic self-assembled nanostructures. The new method opens opportunities for the synthesis of photonic and plasmonic materials with improved long-range ordering.
Installation of the first two front ends for the SLS2.0 completed
At the Swiss Light Source SLS of the Paul Scherrer Institute, another important step has been taken towards the completion of the SLS 2.0 upgrade project.
Insights into the superior oxygen evolution reaction activity of CoOx/CeO2 composite electrocatalyst
CeO2 significantly enhances the oxygen evolution reaction (OER) activity of CoOx, although the mechanism behind this synergy is still unclear. Here, operando hard X-ray absorption spectroscopy (hXAS) is applied to monitor the Co-K edge and Ce L3 edge in CoOx/CeO2 to shed light on the evolution of Co and Ce oxidation states during OER. In addition, ex situ soft XAS (sXAS) characterizations provide information on the irreversible surface-specific transformations of the Co L3 edge as well as the O K edge.
Real-Time Insights into Sodium-Ion Battery Chemistry
Identification of gaseous decomposition products from irreversible side-reactions enables understanding of inner working of rechargeable batteries. Unlike for Li-ion batteries, the knowledge of the gas-evolution processes in Na-ion batteries is limited. Our study revealed that Na-ion cells develop a less stable solid-electrolyte interphase (SEI) compared to Li-ion cells due to higher solubility of SEI constituents in Na-electrolytes.
Anomalous spin precession systematic effects in the search for a muon EDM using the frozen-spin technique
In the paper, the international muEDM collaboration at PSI discusses systematic effects of the most sensitive measurement of the muon's electric dipole moment (EDM). Scientists from Europe are developing a prototype experiment using the frozen-spin technique (FST) to achieve unprecedented sensitivity. The FST meticulously aligns a magnetic field with a perpendicular electric field so that the muon's spin orientation always follows its momentum. This enhances the sensitivity to the muon EDM by about 3 orders of magnitude compared to the best result from the muon g-2 experiment at Brookhaven National Lab.
The paper addresses systematic effects that could mimic an EDM signal when E- and B-fields are not perfectly aligned, adjusted, or stable over time. While most effects cancel out when reversing the magnetic field, some residual effects the specifications for the fields' uniformity, stability, and orientation,
which are challenging but achievable.
Removal of ionic and colloidal 110 mAg from radioactive wastewater using radiografted chelating adsorbents
Nuclear power plays a crucial role in a sustainable future due to its ability to generate large amounts of low-carbon electricity, which is essential for mitigating climate change. Unlike fossil fuels, nuclear energy produces minimal greenhouse gas emissions, helping to reduce the overall carbon footprint of power generation. However, the main concern is the inevitable accumulation of nuclear waste, and this needs to be properly addressed. With the anticipated increase in the number of operating nuclear power plants around the world it is essential to develop new materials and technologies for nuclear waste management. In our latest study we have developed and tested new radiografted materials as potential 110mAg adsorbents. This silver radionuclide is a very elusive contaminant in the pressurized water reactors (PWR) and represents a major problem for normal operation. Additionally, 110mAg possess a significant danger to the environment, if not removed completely from the PWR wastewater.
Towards fast ptychography image reconstruction of EUV masks by deep neural networks
In this study, we explore and demonstrate a rapid method for actinic patterned EUV mask inspection based on a deep neural network (DNN) architecture which exploits a-priori information of the photomask sample. We aim to achieve fast, high-quality image reconstruction of an EUV mask by using comparatively few diffraction patterns in a formalism consistent with the ptychography approach.
We tested our prior-primed DNN method on both synthetic and experimental data, demonstrating that the sample can be reconstructed fast and with high fidelity, allowing us to map out the mask defects down to a size of about 40 nm.
Design and Preclinical Evaluation of a Novel Prostate-Specific Membrane Antigen Radioligand Modified with a Transthyretin Binder
Radioligands targeting the prostate-specific membrane antigen (PSMA) are currently used in the clinics to treat patients with metastatic castration-resistant prostate cancer. Continuous investigations are, nevertheless, conducted to design new small molecule-based radioligands and improve their respective pharmacokinetic properties. Various strategies have been devised to reasonably prolong the blood circulation, which would result into enhanced tumor accumulation and radiation dose delivered to eliminate the cancer cells. The goal of this study was to investigate the influence of the incorporation of a transthyretin binder (TB-01) in the tumor uptake of the resultant PSMA-targeted radioligand.
International collaboration lays the foundation for future AI for materials via the OPTIMADE standard
Artificial intelligence (AI) is accelerating the development of new materials. A prerequisite for AI in materials research is large-scale use and exchange of data on materials, which is facilitated by a broad international standard. A major international collaboration including researchers from the LMS laboratory now presents an extended version of the OPTIMADE standard.
Observation of Mermin-Wagner behavior in LaFeO3/SrTiO3 superlattices
Two-dimensional magnetic materials can exhibit new magnetic properties due to the enhanced spin fluctuations that arise in reduced dimension. However, the suppression of the long-range magnetic order in two dimensions due to long-wavelength spin fluctuations, as suggested by the Mermin-Wagner theorem, has been questioned for finite-size laboratory samples. Here we study ...
Coexistence of Superconductivity and Antiferromagnetism in Topological Magnet MnBi2Te4 Films
The interface of two materials can harbor unexpected emergent phenomena. One example is interface-induced superconductivity. In this work, we employ molecular beam epitaxy to grow a series of heterostructures formed by stacking together two nonsuperconducting antiferromagnetic materials, an intrinsic antiferromagnetic topological insulator MnBi2Te4 and an antiferromagnetic iron chalcogenide FeTe.
Phonon promoted charge density wave in topological kagome metal ScV6Sn6
Charge density wave (CDW) orders in vanadium-based kagome metals have recently received tremendous attention, yet their origin remains a topic of debate. The discovery of ScV6Sn6, a bilayer kagome metal featuring an intriguing √3 × √3 × √3 CDW order, offers a novel platform to explore the underlying mechanism behind the unconventional CDW. Here we combine ...
Promotion versus Poisoning in Copper–Gallium-Based CO2-to-Methanol Hydrogenation Catalysts
Cu–Ga-based CO2-to-methanol hydrogenation catalysts display a range of catalytic performance, depending on their preparation. Here, we investigated how the Ga/Cu ratio and Ga speciation affect the catalytic activity. Using surface organometallic chemistry, we prepared a series of silica-supported 3–6 nm Cu1–xGaxOy nanoparticles with a range of xGa. The materials display a volcano-type activity behavior, where methanol formation is promoted when xGa < 0.13–0.18 and is suppressed at higher values, indicating a poisoning of the catalysts. In situ X-ray absorption spectroscopy and in situ infrared spectroscopy helped to understand the structure-activity relationship.
Optimizing a radiochemical separation of 26Al from an acidic V-rich matrix
At the Paul Scherrer Institute (PSI), within the Isotope and Target Chemistry (ITC) group, various radiochemical methods are developed to fully separate and purify individual radionuclides. These separation methods are devised for both new experiments and for reprocessing radioactive waste from previous experiments.
Non-coplanar helimagnetism in the layered van-der-Waals metal DyTe3
Van-der-Waals magnetic materials can be exfoliated to realize ultrathin sheets or interfaces with highly controllable optical or spintronics responses. In majority, these are collinear ferro-, ferri-, or antiferromagnets, with a particular scarcity of lattice-incommensurate helimagnets of defined left- or right-handed rotation sense, or helicity. Here, we report polarized neutron scattering experiments on DyTe3, whose layered structure has highly metallic tellurium layers separated by double-slabs of dysprosium square nets...
How the orientation of molecular single-ion magnets affects their magnetic hysteresis
Molecular single-ion magnets act as ultra-small magnets that can retain their magnetization. When organized on a well defined surface, they could allow storing information at 100 and more times higher storage densities than nowadays available.
In the present study performed at the Swiss Light Source an international research team investigated monolayers of two very similar types of organometallic single-ion magnets, that, however, behave very differently on a flat silver surface. They link the vastly different magnetic behavior with the different orientation and adsorption configurations on the surface.
Spectral evidence for Dirac spinons in a kagome lattice antiferromagnet
Emergent quasiparticles with a Dirac dispersion in condensed matter systems can be described by the Dirac equation for relativistic electrons, in analogy with Dirac particles in high-energy physics. For example, electrons with a Dirac dispersion have been intensively studied in electronic systems such as graphene and topological insulators. However, charge is not a prerequisite for Dirac fermions, and the emergence of Dirac fermions without a charge degree of freedom has been theoretically predicted to be realized in Dirac quantum spin liquids. These quasiparticles ...
Weyl spin-momentum locking in a chiral topological semimetal
Spin–orbit coupling in noncentrosymmetric crystals leads to spin–momentum locking – a directional relationship between an electron’s spin angular momentum and its linear momentum. Isotropic orthogonal Rashba spin–momentum locking has been studied for decades, while its counterpart, isotropic parallel Weyl spin–momentum locking has remained elusive in experiments. Theory predicts ...
An overview about all-solid-state batteries research activities and characterization capabilities at PSI
All-solid-state batteries (ASSBs) are forecasted to play a central role in the next generation of high energy density and safe storage devices. However, ASSBs still an immature technology and require further advancements on multiple fronts like interface (electro-)chemical and mechanical instabilities. Here, we provide an overview about PSI efforts in (i) employing advanced operando laboratory and synchrotron-based analytical methods to shed light into the various degradation mechanisms and (ii) our capabilities for interface chemical engineering.
Breaking the Drops
For water-cooled nuclear reactors, a loss of coolant accident constitutes one of the key scenarios to be evaluated for the design of the plant and associated safety systems. Even if these accidents are not expected to occur at all during reactor lifetime, their potential consequences include the heat up of the fuel in the reactor core. For the recovery of the plant to safe conditions, safety systems are in place to inject water in order to reflood the core and to quench the high temperature fuel. The two-phase flow behaviour during this reflooding phase is extremely complex. In particular, the prediction of the behaviour of small liquid droplets generated as the quench front propagates upwards has a significant effect on the fuel temperatures in the upper regions of the reactor core. In collaboration with the US Nuclear Regulatory Commission (NRC), we have been working to improve our modelling of the droplet behaviour and their impact on key safety parameters.
Dr. Chiara Favaretto has been honored with the Alavi-Mandell Award 2024
We congratulate Dr. Chiara Favaretto for the excellent research work she did during her time at the Center for Radiopharmaceutical Sciences.
Three-dimensional magnonics
Researchers from an international collaboration between Switzerland, Italy, and Germany have performed the first time-resolved imaging at sub-ns timescales of the three-dimensional propagation dynamics of a spinwave in a synthetic antiferromagnetic nanostructured device, opening up the possibility to investigate magnon dynamics in complex three-dimensional geometries.
Surface oxidation/spin state determines oxygen evolution reaction activity of cobalt-based catalysts in acidic environment
Co-based catalysts are promising candidates to replace Ir/Ru-based oxides for oxygen evolution reaction (OER) catalysis in an acidic environment. However, both the reaction mechanism and the active species under acidic conditions remain unclear. In this study, by combining surface-sensitive soft X-ray absorption spectroscopy characterization with electrochemical analysis, we discover that the acidic OER activity of Co-based catalysts are determined by their surface oxidation/spin state.
All Two-Loop Feynman Integrals for Five-Point One-Mass Scattering
We compute the complete set of two-loop master integrals for the scattering of four massless particles and a massive one. Our results are ready for phenomenological applications, removing a major obstacle to the computation of complete next-to-next-to-leading order QCD corrections to processes such as the production of a H/Z/W boson in association with two jets at the LHC. Furthermore ...
Polybenzimidazole Membrane Design Principles for Vanadium Redox Flow Batteries
Energy storage technologies with long storage duration are essential to stabilize electricity grids with a high share of intermittent renewable power. In a redox flow battery, the electrochemical conversion unit, where the charging and discharging reaction takes place, is spatially separated from the energy storage medium. In the all-vanadium redox flow battery (VRFB), a sulfuric acid aqueous electrolyte with dissolved vanadium ions is used as the storage medium. Vanadium is present in 4 different oxidation states, the redox couple vanadium(II) and (III) on the negative side of the cell, and vanadium(IV) and (V) on the positive side. This allows the battery to be repeatedly charged and discharged. A separator or membrane is used between the negative and positive electrode, which should selectively conduct the ions of the supporting electrolyte and minimize the passage of vanadium ions. Fluorinated membranes, such as Nafion™, are often used for this key component, but these ionomers were not originally developed for this application and therefore have functional shortcomings. Furthermore, the production and use of fluorinated materials is to be severely restricted or even banned in Europe. Therefore, the development of hydrocarbon-based membranes for the VRFB is of great importance. The study reported here focuses on polybenzimidazole polymers and membranes, which could be a promising materials class for next generation flow batteries.
High-resolution ptychographic imaging at a seeded free-electron laser source using OAM beams
Electromagnetic waves possessing orbital angular momentum (OAM) are powerful tools for applications in optical communications, quantum technologies, and optical tweezers. Now, a consortium of collaborators in France, Italy, Slovenia, Spain, Switzerland, Sweden, and the US reports on using such beams in the extreme ultraviolet region for ptychographic imaging in the cover page article of Optica 11, Issue 3. By controlling the topological charge, the researchers achieve an improvement of 30% in image resolution.
Electron Glass Phase with Resilient Zhang-Rice Singlets in LiCu3O3
LiCu3O3 is an antiferromagnetic mixed valence cuprate where trilayers of edge-sharing Cu(II)O (3d9) are sandwiched in between planes of Cu(I) (3d10) ions, with Li stochastically substituting Cu(II). Angle-resolved photoemission spectroscopy (ARPES) and density functional theory reveal two insulating electronic subsystems that are segregated in spite of sharing common oxygen atoms: a Cu dz2/O pz derived valence band (VB) dispersing on the Cu(I) plane, and a Cu 3dx2−y2/O 2px,y derived Zhang-Rice singlet (ZRS) band dispersing on the Cu(II)O planes.
Flat-band hybridization between f and d states near the Fermi energy of SmCoIn5
We present high-quality angle-resolved photoemission (ARPES) and density functional theory calculations (DFT+U) of SmCoIn5. We find broad agreement with previously published studies of LaCoIn5 and CeCoIn5, confirming that the Sm 4f electrons are mostly localized. Nevertheless, our model is consistent with an additional delocalized Sm component, stemming from hybridization between the 4f electrons and the metallic bands at “hot spot” positions in the Brillouin zone.
Efficient transient X-ray absorption spectroscopy
By combining the unique large bandwidth emission mode of SwissFEL’s ARAMIS undulator and diffractive X-ray optics made of diamond, we have demonstrated a new method for time-resolved X-ray absorption near edge structure (XANES) spectroscopy that enables faster data acquisition and requires smaller sample quantities for high-quality data.
Microfluidic platform for in situ characterization of heterogenous catalysts
A deep understanding of active site architectures during surface-catalyzed reactions is a crucial step for the design of recyclable heterogeneous catalysts for organic synthesis. In this work, a droplet-based microfluidic setup was developed and applied to perform Suzuki-Miyaura coupling over heterogenous single-atom Pd-catalyst.
2024 SPIE Advanced Lithography + Patterning, San Jose, California
2024 SPIE Advanced Lithography + Patterning symposium hosted leading researchers who are solving challenges in optical and EUV lithography, patterning technologies, metrology, and process integration for semiconductor manufacturing and adjacent applications. The symposium features six conference topics.
The Tipping Point!
Exciting to see that some of our research on Narwhal tusk made it into an educational videogame about climate change in the Arctic and its impact on some of its inhabitants!
Introduction to Muon Spin Spectroscopy
Alex Amato and Elvezio Morenzoni have published a new textbook entitled 'Introduction to Muon Spin Spectroscopy: Applications to Solid State and Material Sciences'. The book is ideal for a first course in muon spin spectroscopy (µSR), comes enriched with exercises and solutions to master the subject and includes practical examples to quantify key experimental parameters.
Observation by SANS and PNR of pure Néel-type domain wall profiles and skyrmion suppression below room temperature in magnetic [Pt/CoFeB/Ru]10 multilayers
The study presents a unique investigation of [Pt/CoFeB/Ru]10 multilayers, revealing suppressed skyrmion phases, intricate magnetic domain structures, and Néel-type domain walls, providing crucial insights for spintronic applications.
Spatially reconfigurable topological textures in freestanding antiferromagnetic nanomembranes
Researchers from the University of Oxford have imaged, through the use of the soft X-ray microscopy capabilities at the Swiss Light Source, spatially reconfigurable antiferromagnetic states in topologically rich free-standing nanomembranes
Unraveling degradation processes in a bipolar membrane CO2 electrolyzer by time-resolved X-ray tomographic microscopy
Employing a bipolar ion conducting membrane (BPM) in forward bias is a convenient solution for the biggest issues in the more common anion exchange membrane (AEM) CO2 co-electrolysis: the degradation of the performance caused by carbonate salt precipitation at the cathode and the decrease of net CO2 conversion caused by the crossover of this molecule from cathode to anode also requiring energy for downstream gas separation. However, the performance and stability of this device remain largely insufficient when using such a BPM configuration. To understand the reasons for this, we performed time-resolved X-ray tomographic microscopy of an operating BPM CO2 electrolyzer. The imaging method reveals partly unexpected degradation processes that result in design recommendations for improvement.
Ptychographic Nanoscale Imaging of the Magnetoelectric Coupling in Freestanding Bismuth Ferrite Films
Through soft X-ray ptychographic imaging, researchers at the Swiss Light Source have directly imaged the magneto-electric coupling between the ferroelectric domain structure and the spin-cycloidal state in freestanding BiFeO3 thin films.
Phonon promoted charge density wave in topological kagome metal ScV6Sn6
Charge density wave (CDW) orders in vanadium-based kagome metals have recently received tremendous attention, yet their origin remains a topic of debate. The discovery of ScV6Sn6, a bilayer kagome metal featuring an intriguing √3 × √3 × √3 CDW order, offers a novel platform to explore the underlying mechanism behind the unconventional CDW. Here we combine ...
SRF material research using muon spin rotation and beta-detected nuclear magnetic resonance
Muon spins precess in transverse magnetic fields and emit a positron preferentially in the spin direction at the instant of decay, enabling muon spin rotation (μSR) as a precise probe of local magnetic fields in matter. μSR has been used to characterize superconducting radio-frequency (SRF) materials since 2010. At TRIUMF, a beam of 4.2 MeV μ+ is implanted at a material-dependent depth of approximately 150 μm. A dedicated spectrometer was developed to measure the field of first vortex penetration and pinning strength in SRF materials in parallel magnetic fields of up to 300 mT. A low-energy beam available at PSI implants μ+ at variable depth in the London layer allowing for direct measurements ...
Tuning of the flat band and its impact on superconductivity in Mo5Si3−xPx
The superconductivity in systems containing dispersionless (flat) bands is seemingly paradoxical, as traditional Bardeen-Cooper-Schrieffer theory requires an infinite enhancement of the carrier masses. However, the combination of flat and steep (dispersive) bands within the multiple band scenario might boost superconducting responses, potentially explaining high-temperature superconductivity in cuprates and metal hydrides. Here, we report ...
Interface-induced superconductivity in magnetic topological insulators
One of the recipes for realizing topological superconductivity calls for interfacing a topological insulator with a superconductor. In a variant of that approach, Yi et al. grew a heterostructure consisting of layers of a magnetic topological insulator, (Bi,Sb)2Te3 doped with chromium, and antiferromagnetic iron telluride. Neither of these materials is superconducting, but iron telluride is a parent compound for a family of iron-based superconductors. Interfacing the layers led to the appearance of superconductivity in the presence of ferromagnetism and topological band structure. This combination of properties makes the heterostructure a promising, although not yet proven, platform for observing chiral topological superconductivity.
Extreme ultraviolet for scalable silicon quantum devices
Experiments at the Swiss Light Source (SLS) show the potential of extreme ultraviolet light (EUV) to make the building blocks of scalable quantum computers.
Unravelling the amorphous structure and crystallization mechanism of GeTe phase change memory materials
Here we use in-situ high-temperature x-ray absorption spectroscopy (XAS) and theoretical calculations to quantify the amorphous structure of bulk and nanoscale GeTe. Based on XAS experiments, we develop a theoretical model of the amorphous GeTe structure, consisting of a disordered fcc-type Te sublattice and randomly arranged chains of Ge atoms in a tetrahedral coordination.
Short x-ray pulses reveal the source of light-induced ferroelectricity
Ultrafast measurements of the fluctuating atomic positions in the quantum paraelectric SrTiO3 after mid-infrared light excitation, reveal details about the creation of the material’s ferroelectric state.
Insights into the superior oxygen evolution reaction activity of CoOx/CeO2 composite electrocatalyst
CeO2 significantly enhances the oxygen evolution reaction (OER) activity of CoOx, although the mechanism behind this synergy is still unclear. Here, operando hard X-ray absorption spectroscopy (hXAS) is applied to monitor the Co-K edge and Ce L3 edge in CoOx/CeO2 to shed light on the evolution of Co and Ce oxidation states during OER. In addition, ex situ soft XAS (sXAS) characterizations provide information on the irreversible surface-specific transformations of the Co L3 edge as well as the O K edge.
Machine Learning for Quantitative Structural Information from Infrared Spectra: The Case of Palladium Hydride
Infrared spectroscopy (IR) is a widely used technique enabling to identify specific functional groups in the molecule of interest based on their characteristic vibrational modes or the presence of a specific adsorption site based on the characteristic vibrational mode of an adsorbed probe molecule. The interpretation of an IR spectrum is generally carried out within a fingerprint paradigm by comparing the observed spectral features with the features of known references or theoretical calculations. This work demonstrates a method for extracting quantitative structural information beyond this approach by application of machine learning (ML) algorithms.
"Magnetostriction-Driven Muon Localization in an Antiferromagnetic Oxide" published in Phys. Rev. Lett.
A study involving PSI scientists from the LMS lab, and just published in Physical Review Letters has found that in manganese oxide, a textbook antiferromagnetic material, the site of an implanted spin-polarized muon is not well identified, but can change due to a previously neglected effect: magnetostriction.