Dr. Yingfang He has been honored with the Alavi-Mandell Award 2025
We congratulate Dr. Yingfang He for the excellent research work she did during her time at the Center for Radiopharmaceutical Sciences.
Nanostructure orientation in 3D with visible light by Tomographic Müller-Polarimetric Microscopy
We developed a new method, tomographic Müller-polarimetric microscopy (TMPM), that allows to retrieve at three-dimensional microscopic resolution the nanoscale structural information of the ultrastructure probed with polarized light in a non-destructive manner using a low cost and experimentally simple optical setup.
Spin density wave and van Hove singularity in the kagome metal CeTi3Bi4
Kagome metals with van Hove singularities near the Fermi level can host intriguing quantum phenomena such as chiral loop currents, electronic nematicity, and unconventional superconductivity. However, to our best knowledge, unconventional magnetic states driven by van Hove singularities–like spin-density waves–have not been observed experimentally in kagome metals. Here, we report ...
Primer on X-ray magnetic circular dichroism
X-ray magnetic circular dichroism (XMCD) is a magneto-optical effect that describes the difference in absorption between left and right circularly polarized X-rays by a magnetized material. It has been widely applied to the study of magnetic systems and of magnetic phenomena and its unique capabilities make it a fundamental tool for the study of novel magnetic phenomena and new materials systems.
Advancing Biogas Quality: Tackling Siloxane Challenges for Smooth Energy Transition
Siloxanes, present in everyday items, can compromise the efficiency and durability of bioenergy systems, even at trace levels. Monitoring and quantifying these impurities are critical for improving biogas quality and expanding its role in renewable energy. However, sampling biogas and storing samples containing siloxanes for analysis remain a significant challenge.
Correlating transmission electron and soft x-ray microscopy to bridge atomic- and mesoscales
Transmission electron and soft x-ray microscopy have contributed significantly to our understanding of phenomena in fields ranging from biology to materials science. In this review, we present recent developments in combining transmission electron and soft x-ray microscopy techniques, including progress in sample environment, and in situ and operando approaches and highlight the unique opportunities offered by fully correlative transmission electron and soft x-ray microscopy.
Antiferrodistortive and ferroeletric phase transitions in freestanding films of SrTiO3
Epitaxially grown thin films are commonly used to strain engineer electronic properties by the choice of a substrate, and therefore do not match bulk properties (leading to properties that deviate from the bulk material). Free standing ultrathin oxide films are expected to preserve the bulk-like properties due to the absence of substrate influence. However, we show that this expectation is not fulfilled with ultrathin free standing SrTiO3, as they get ferroelectric at 80K.
Superconductivity and a van Hove singularity con ned to the surface of a topological semimetal
The interplay between topology and superconductivity generated great interest in condensed matter physics. Here, we unveil an unconventional two-dimensional superconducting state in the Dirac nodal line semimetal ZrAs2 which is exclusively con ned to the top and bottom surfaces within the crystal’s ab plane.
As a remarkable consequence ...
Momentum-resolved fingerprint of Mottness in layer-dimerized Nb3Br8
Crystalline solids can become band insulators due to fully lled bands, or Mott insulators due to strong electronic correlations. While Mott insulators can theoretically occur in systems with an even number of electrons per unit cell, distinguishing them from band insulators experimentally has remained a longstanding challenge.
In this work, we present ...
Emergence of topological Hall effect from a fluctuation-based dynamic origin
The topological nature of the electronic bands or spin structure has direct manifestation in experimentally measured Hall conductivity. The extra topological (or geometrical) component to the Hall effect (THE) usually emerges due to multi-k structures, which inherently possess a finite static scalar spin chirality (SSC). Generating a THE in a single-k structure necessitates the consideration of the dynamical origin of SSC, the real material examples of such cases remain scarce to date.
Water gets in shape for VUV absorption
Nanometre‑thin, free‑flowing liquid sheets now let Swiss Light Source users record pristine VUV absorption spectra of water, and soon any solvent.
Zero-field Hall effect emerging from a non-Fermi liquid in a collinear antiferromagnet V1/3NbS2
Magnetically intercalated transition metal dichalcogenides (TMDs) provide a versatile three-dimensional (3D) material platform to explore quantum phenomena and functionalities that emerge from an intricate interplay among magnetism, band structure, and electronic correlations.
Generation of Neutron Airy Beams
The Airy wave packet is a solution to the potential-free Schrödinger equation that exhibits remarkable properties such as self-acceleration, nondiffraction, and self-healing. Although Airy beams are now routinely realized ....
Texture analysis implementation at the neutron strain diffractometer POLDI
This study presents the implementation of a novel data analysis methodology to perform spatially resolved crystallographic texture analyses in bulk specimens at POLDI, the pulsed frame overlap diffractometer at SINQ, Paul Scherrer Institute. The method is based on the determination of several incomplete pole figures. To increase the angular resolution, the POLDI diffraction bank is split into several virtual units of smaller angular coverage. The diffraction data of each virtual unit can then be analyzed individually and used to create experimental pole figures from the Euler angles of the explored sample orientations. Additionally, to help the analyses, a new numerical tool was developed and implemented at POLDI to calculate neutron flight path of each virtual detector as a function of sample size, geometry, and orientation. Leveraging on the SALOME platform’s Geom module (open-source CAD modeler), the tool allows inserting CAD objects into a virtual detailed PODI geometry. This allows to automate sample positioning and orientation within the instrument frame and computes flight path intersections. It serves two main purposes: enhancing texture analysis through precise path calculations and aiding experimental design by visually evaluating orientation feasibility and estimating counting times. Finally, to complete the analysis path from the experiments to the results, the experimental and numerical evaluations are processed together with POLTex (MATLAB-based toolbox) to obtain the orientation distribution functions. To demonstrate the analysis routine, the crystallographic texture of an additively manufactured steel sample and Zircaloy-4 sample were characterized.
Mapping crystallite orientation in bulk polycrystals
A new experimental technique allows the orientation distribution of small-grained polycrystal materials to me mapped in 3D.
Defect structure controls the thermal magnetic switching rate of nano-sized metallic particles.
Past experiments done at the Paul Scherrer Institut, probed the thermal switching properties of nano-sized metallic magnetic particles
PILATUS4 detector arrives at PXIII
On April 4, 2025, a Dectris Pilatus4 2M detector was successfully installed at beamline PXIII. In the coming weeks, this new detector will be used to measure the first macromolecular crystallography (MX) experiments using the SLS 2.0 machine.
Yielding behaviour of active particles in bulk and in confinement
We computationally investigate the transition from rigid to flowing states in dense assemblies of self-propelled particles. Such theoretical representations of biological assemblies have yielded tremendous insight into collective behaviour across many scales, from bird flocks, through bacterial colonies, tissue organisation and including sub-cellular assemblies such as the cytoskeleton. Of particular interest to us are observations of dramatic changes in the dynamics of chromatin within cell nuclei, understood to undelie changes in biological state and function. Dynamics in this context is controlled by the strength and temporal persistence of out-of-equilibrium mechanical perturbations, as well as the geometry of confinement. Evidence of a transition from rigid to flowing states across a critical perturbation strength, strongly reminiscent of yielding in externally deformed amorphous solids, motivates us to explore this analogy, and to investigate the role of persistence time and confinement geometry on the transition.
Dynamical transitions in dense packings
Biophysical modeling points to changes in collective dynamics under confinement as a key aspect of cell state transitions.
Vacancy-induced suppression of charge density wave order and its impact on magnetic order in kagome antiferromagnet FeGe
Two-dimensional (2D) kagome lattice metals are interesting because their corner sharing triangle structure enables a wide array of electronic and magnetic phenomena. Recently, post-growth annealing is shown to both suppress charge density wave (CDW) order and establish long-range CDW with the ability to cycle between states repeatedly in the kagome antiferromagnet FeGe.
Here we perform ...
Rethinking 3D Printing for ceramics
Using a powerful combination of in-situ X-ray imaging and high-fidelity simulations, researchers uncover how alumina behaves under laser-based 3D printing—paving the way for more reliable ceramic additive manufacturing.
Anomalous Hall Effect due to Magnetic Fluctuations in a Ferromagnetic Weyl Semimetal
The anomalous Hall effect (AHE) has emerged as a key indicator of time-reversal symmetry breaking (TRSB) and topological features in electronic band structures. Absent of a magnetic field, the AHE requires spontaneous TRSB but has proven hard to probe due to averaging over domains. The anomalous component of the Hall effect is thus frequently derived from extrapolating the magnetic field dependence of the Hall response. We show ....
Rhodium recovery from acidic wastewater using radiografted chelating adsorbents
Platinum group metals (PGMs), particularly rhodium (Rh), are rare and vital for industrial applications, with Rh being scarcer (≈ 20 t/y) than platinum (Pt) and palladium (Pd). Its high cost and limited supply emphasize the need for efficient recovery from industrial waste. New radiografted chelating adsorbents, created through irradiation, offer a sustainable, cost-effective alternative to existing extraction methods. They exhibit high efficiency, selectivity, and reusability, making them ideal for recovering and recycling Rh from industrial wastewater.
Two Characteristic Contributions to the Superconducting State of 2H-NbSe2
Multiband superconductivity arises when multiple electronic bands contribute to the formation of the superconducting state, allowing distinct pairing interactions and gap structures. Here, we present field- and temperature-dependent data ...
Observation of the spiral spin liquid in a triangular-lattice material
The spiral spin liquid (SSL) is a highly degenerate state characterized by a continuous contour or surface in reciprocal space spanned by a spiral propagation vector. Although the SSL state has been predicted in a number of various theoretical models, very few materials are so far experimentally identified to host such a state. Via combined single-crystal wide-angle and small-angle neutron scattering, we report observation ...
Generating a highly uniform magnetic field inside the magnetically shielded room of the n2EDM experiment
The central magnetic field of the n2EDM experiment based at PSI is of paramount importance for achieving the sensitivity goal. The necessary field homogeneity was recently demonstrated, as described here.
Doping dependence of the dipolar correlation length scale in metallic SrTiO3
Superconducting domes, ubiquitous across a variety of quantum materials, are often understood as a window in which pairing is favored, opened by the fluctuations of competing orders. Yet, the understanding of how such a window closes is missing. Here, we show that inelastic neutron scattering ...
Key reaction steps in the simultaneous conversion of nitrous and nitric oxides on Fe-ZSM-5
After proposing the reaction mechanism of the N2O-NO-SCR reaction on Fe-FER, here we attempted at controlling the Fe speciation on ZSM-5 and at generalizing the result obtained on FER.
Confining surface oxygen redox in double perovskites for enhanced oxygen evolution reaction activity
Nickel-based double perovskites AA’BB’O6 are an underexplored class of oxygen evolution reaction (OER) catalysts. In particular, BaSrNiWO6 exhibits high oxygen evolution activity, attributed to the evolution of a highly OER active surface phase. The redox transformation of Ni2+(3d8) to Ni3+(3d7) combined with partial W dissolution into the electrolyte drives an in-situ reconstruction of the surface to an amorphized, NiO-like layer, promoting oxygen redox in the OER mechanism.
Pressure-enhanced splitting of density wave transitions in La3Ni2O7–δ
The observation of superconductivity in La3Ni2O7–δ under pressure, following the suppression of a high-temperature density wave state, has attracted considerable attention. The nature of this density wave order was not clearly identified. Here we probe the magnetic response of the zero-pressure phase of La3Ni2O7–δ as hydrostatic pressure is applied, and find that the apparent single density wave transition at zero applied pressure splits into two. The comparison of our muon-spin rotation ...
Outstanding Paper Award
A recent paper by the "Applied Materials Group" of the LNS and their coworkers received the "Outstanding Paper Award" of the journal "Materials and Structures".
Spin-orbit control of antiferromagnetic domains without a Zeeman coupling
Encoding information in antiferromagnetic (AFM) domains is a promising solution for the ever growing demand in magnetic storage capacity. The absence of a macroscopic magnetization avoids crosstalk between different domain states, enabling ultrahigh density spintronics while being detrimental to the domain detection and manipulation. Disentangling these merits and disadvantages seemed so far unattainable. We report evidence ...
Electronic Commensuration of a Spin Moiré Superlattice in a Layered Magnetic Semimetal
Spin moiré superlattices (SMSs) formed by interfacing conventional electronic states with a multi-q magnetic lattice have been proposed as a magnetic analog of crystallographic moiré systems. The electron-minibands created in an SMS are expected to be enriched by the vector-field nature of the magnetic interaction and offer new types of moiré tunability, topological protection, and Berry curvature effects. However, most spin-vortex-hosting systems discovered to date have carrier mean free paths lmfp significantly shorter than their spin-moiré lattice constant aspin, inhibiting mini-band-formation. Furthermore ...
Evolution of texture and residual stresses in 2205 duplex stainless steel during laser powder bed fusion
This study uses a custom-designed laser powder bed fusion machine, capable of operating in neutron instruments, to track metallic material evolution during additive manufacturing process. More specifically, it investigates the development of residual stresses in textured 2205 duplex stainless steel during laser powder bed fusion. In situ and operando neutron diffraction experiments were conducted to study the transient and real-time evolution of stresses and strains during processing, using an AM machine designed for neutron studies. Additionally, Bragg-edge imaging was employed to investigate the crystallographic texture. The results showed that residual stress redistribution primarily occurs in the first set of added layers when further layers are added on top. The cube texture observed in the sample significantly affects residual stress determination, leading to inaccuracies up to 96 MPa if not accounted for. This highlights the need for orientation-dependent diffraction elastic constants in residual stress calculations. Furthermore, variations in texture intensity across the sample dimensions were found to be driven by changes in the local temperature history, which were deciphered from real-time strain measurements. Finally, this study demonstrates the potential of combining laser powder bed fusion with neutron diffraction to investigate the underlying mechanisms of additive manufacturing in the bulk of the sample.
Anisotropic Skyrmion and Multi-q Spin Dynamics in Centrosymmetric Gd2PdSi3
Skyrmions are particlelike vortices of magnetization with nontrivial topology, which are usually stabilized by Dzyaloshinskii-Moriya interactions (DMI) in noncentrosymmetric bulk materials. Exceptions are centrosymmetric Gd- and Eu-based skyrmion-lattice (SL) hosts with zero DMI, where both the SL stabilization mechanisms and magnetic ground states remain controversial. We address these here by investigating both the static and dynamical spin properties ...
Texture and residual stress evolution during 3D printing
Discover how advanced neutron diffraction sheds light on the evolution of stress and texture in 3D-printed duplex stainless steel.
Mapping the ecosystem of Wannier Functions software
A new review article, just published in Reviews of Modern Physics and highlighted on the journal cover, provides a map to the vast landscape of software codes that allow researchers to calculate Wannier functions, and to use them for materials properties predictions. The authors, from all over Europe and the USA, include two PSI scientists. After providing readers with the theoretical foundations on Wannier functions and their calculation, together with intuitive graphical schematics to explain what Wannier functions are, the authors map the existing Wannier codes and the key applications.
Operando phase mapping in multi-material laser powder bed fusion
This study introduces a custom-designed laser powder bed fusion machine, capable of operating in neutron instruments, to track material evolution during additive manufacturing. Using neutron imaging, this study uncovers how complex thermal cycling impacts phase development in multi-material parts, offering new insights into optimizing additive manufacturing processes and enhancing material properties for more precise and high-performance components.
Concurrent Operando Neutron Imaging and Diffraction Analysis Revealing Spatial Lithiation Phase Evolution in an Ultra-Thick Graphite Electrode
Energy-efficient, safe, and reliable Li-ion batteries (LIBs) are required for a wide range of applications. The introduction of ultra-thick graphite anodes, desired for high energy densities, meets limitations in internal electrode transport properties, leading to detrimental consequences. Yet, there is a lack of experimental tools capable of providing a complete view of local processes. Here, a multi-modal operando measurement approach is introduced, enabling quantitative spatio-temporal observations of Li concentrations and intercalation phases in ultra-thick graphite electrodes.
Neutron imaging and diffraction concurrently provide ...
Understanding the Interplay between Artificial SEI and Electrolyte Additives in Enhancing Silicon Electrode Performance for Li-Ion Batteries
Maintaining a stable solid electrolyte interphase (SEI) is crucial for Li-ion battery safety, especially with high-capacity anode containing silicon. Therefore, our study explored long-term cycling of Si electrodes with artificial alucone-based SEI, deposited by molecular layer deposition (MLD) in combination with a fluoroethylene carbonate (FEC) electrolyte additive. MLD of flexible Li-ion permeable artificial SEI coatings onto electrode resulted in improved capacity, enhanced Si electrode cycle life and capacity retention.
Operando Neutron Characterization During 3D Printing
A new laser powder bed fusion device enables real-time neutron diffraction and imaging, providing detailed insights into structural evolution, defect formation, and temperature mapping during metal additive manufacturing.
YBa1−𝑥Sr𝑥CuFeO5 layered perovskites: An attempt to explore the magnetic order beyond the paramagnetic-collinear-spiral triple point
Layered perovskites of general formula AA'CuFeO5 are characterized by the presence of spiral magnetic phases whose ordering temperatures 𝑇spiral can be tuned far beyond room temperature by introducing modest amounts of Cu/Fe chemical disorder in the crystal structure. This rare property makes these materials prominent candidates to host multiferroicity and magnetoelectric coupling at temperatures suitable for applications. Moreover, it has been proposed that the highest 𝑇spiral value that can be reached in this structural family ( ∼400 K) corresponds to a paramagnetic-collinear-spiral triple point with potential to show exotic physics. Since generating high amounts of Cu/Fe disorder is experimentally difficult, the phase diagram region beyond the triple point has been barely explored. To fill this gap we investigate here eleven YBa1−𝑥Sr𝑥CuFeO5 solid solutions (0≤𝑥≤1 ), where we replace Ba with Sr with the aim of enhancing the impact of the experimentally available Cu/Fe disorder. Using a combination of bulk magnetization measurements, synchrotron x-ray and neutron powder diffraction we show that the spiral state with 𝐤𝑠=(1/2,1/2,1/2±𝑞) is destabilized beyond a critical Sr content, being replaced by a fully antiferromagnetic state with ordering temperature 𝑇coll2≥𝑇spiral and propagation vector 𝐤𝑐2=(1/2,1/2,0). Interestingly, both 𝑇spiral and 𝑇coll2 increase with 𝑥 with comparable rates. This suggests a common, disorder-driven origin for both magnetic phases, consistent with theoretical predictions.
Connection between f-electron correlations and magnetic excitations in UTe2
The detailed anisotropic dispersion of the low-temperature, low-energy magnetic excitations of the candidate spin-triplet superconductor UTe2 is revealed using inelastic neutron scattering. The magnetic excitations emerge from the Brillouin zone boundary at the high symmetry Y and T points and disperse along the crystallographic b-axis. In applied magnetic fields ...
Decentralized hydrogen-based stationary energy storage systems complemented by smart control can provide increased operational flexibility in the energy system
While the electrification of the energy system implies a reduction of greenhouse gas emissions greatly beneficial to society, it can also pose technical challenges. The most notable among these are that the capacity of the local electric grid may be exceeded, along with the occurrence of imbalances between decentralized renewable energy production and final consumption. Hydrogen-based energy storage systems (HESS) are regarded as promising solutions to address these challenges. However, the feasibility has not been demonstrated and the involved processes are not well characterized on a technical relevant power level, so far.
Small-angle scattering interferometry with neutron orbital angular momentum states
Methods to prepare and characterize neutron helical waves carrying orbital angular momentum (OAM) were recently demonstrated at small-angle neutron scattering (SANS) facilities. These methods enable access to the neutron orbital degree of freedom which provides new avenues of exploration in fundamental science experiments as well as in material characterization applications.
However, ....
Mitigating Cracks in Multi-Material Printing
Integrating metallic powders with thin foils in laser powder bed fusion can reduce interfacial cracks and improve microstructure quality in titanium-aluminum multi-material printing.
Fractional quasiparticles in three dimensions
Specific signatures of fractionalization have been observed in a three-dimensional system known as quantum spin ice.
Evidence of antiferromagnetism in ultrathin metallic (111)-oriented LaNiO3 films
Antiferromagnets with exotic spin textures promise low-power spintronic devices with extremely high operating frequencies and resistance to external perturbations. In particular, the combination of highly tunable correlated electron physics, as in complex oxides, with metallicity and antiferromagnetism is desirable but exceedingly rare. LaNiO3, the lone example of a perovskite nickelate which is metallic across all temperatures, has long been a promising candidate, but the antiferromagnetic metallic state has remained elusive. We demonstrate the emergence ...