Lab News & Scientific Highlights

The authors find using resonant and non-resonant x-ray diffraction on an x-ray free electron laser that the structural distortion and the underlying electronic structure of the charge density wave in TiSe₂ show different energetics at ultrafast timescales. This indicates that the lattice distortion stabilizes the charge density wave.

FEL-based ultrafast calorimetry measurements show enhancement and maximum in the isobaric specific-heat.

The first experimental observation of three-dimensional magnetic ‘vortex rings’ provides fundamental insight into intricate nanoscale structures inside bulk magnets, and offers fresh perspectives for magnetic devices.

The interaction of light and magnetism at the nanoscale is a topic of fundamental interest and with potential impact to future spintronics applications. in this work we address theoretically and experimentally the effect of femtosecond laser pulse excitation on the magnetic, structural, and chemical stability of individual magnetic cobalt nanoparticles including the role of the substrate or matrix. Eventually, we discuss possible pathways to achieve laser-induced magnetic switching in individual nanostructures.

This work has been highlighted as "Editors' Suggestion" in Physical Review B.

The structural changes of Na3.32Fe2.11Ca0.23(P2O7)2 during several charge discharge cycles is viewed by its powder pattern and selected cell parameter evolution.

A cyan light (492 nm) emitting colloidal suspension of CsPbBr₃ nanoplatelets in a flask, together with the high-quality XRPD Total Scattering pattern of the suspension measured at the X04SA-MS beamline and the full-nanoparticle structure thereby inferred.

Der Kanton Aargau unterstützt das Technologietransferzentrum Anaxam in Villigen für die Dauer von vier Jahren mit insgesamt 2,4 Millionen Franken. Der Grosse Rat hat am Dienstag in Spreitenbach den entsprechenden Kredit mit 124 zu 3 Stimmen bewilligt.

Ultra-fast operando X-ray diffraction experiments reveal the temporal evolution of low and high temperature phases and the formation of residual stresses during laser 3D printing of a Ti-6Al-4V alloy. The profound influence of the length of the laser-scanning vector  on the evolving microstructure is revealed and elucidated.  

Magnonic crystals are periodic magnetic structures, which are attracting great interest because of their potential use in low-power information technology based on spin waves, or magnons. Artificial spin ices have been recently studied as reconfigurable magnonic crystals, but achieving the required combination of magnetic state reconfigurability and desired magnon dispersions remains challenging. Here, researchers propose a hybrid system that makes use of a magnetic thin film underlayer to couple and strengthen the interaction between the artificial spin ice’s nanoelements though spin waves. Moreover, the magnetic state of the artificial spin ice gives rise to directional spin wave channels in the underlayer. This hybrid system opens a new direction for band structure engineering in reconfigurable magnonic crystals.

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.

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.

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.

Sebastian Gliga has been awarded an SNF Spark grant to investigate the possibility of combining magnetic thin films with graphene to create logical devices. As electronic components, such as those found in computer CPUs, are miniaturized, they generate waste heatand alternative schemes are being explored to create novel data processing architectures. This project, to be carried out in the Microspectroscopy group (PSD), aims to exploit the tunable topography of graphene to create magnetic systems, which allow simultaneously guiding spin waves and performing logical operations based on spin wave interference. 

Organic–inorganic ‘hybrid’ perovskites have recently gained attention as a low-cost alternative to silicon solar cells. However, many properties of these materials are still poorly understood. In particular, how imperfections in the crystals, which can be both static or dynamic, affect energy transport remains unclear.

X-rays and neutrons has been used to investigate the correlation between structural and magnetic chirality in magnetic fields and its impact on the polarization in multiferroic langasites. A long wavelength modulation of the magnetic structure has been found, and it is shown that the chirality of the crystals structure connects to chirality of the magnetic structure that leads to an additional electric polarization in this field induced phase, which, depending on the christal chirality, can either increase the electric polarization or lead to a reversal of it for increasing magnetic fields. The theoretical description based on allowed Lifshitz invariants intriguingly contain all the essential ingredients for the realization of topologically stable antiferromagnetic skyrmions.

Interrupted standard tensile tests with in situ x-ray diffraction and quasi-in situ electron backscatter diffraction reveal the origin behind the work hardening plateau and springback.

Via femtosecond x-ray diffraction, we observe an ultrafast increase of the octahedral rotation angle in the perovskite EuTiO₃ after ultrafast laser excitation. This is opposite to what is expected from an increase in temperature. We ascribe this increase to an effective change of ionic sizes that transforms directly into a change of the Goldschmidt tolerance factor. Rotating oxygen octahedra at will opens up the possibility to control electronic and magnetic properties of perovskites on ultrafast timescales.

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

The progressive hydrostatic compression of I2 and I3- units in an organic salt lead to a homoatomic polymeric chain. As the I---I distance collapses the covalent character of the interaction becomes more relevant, leading to a pressure-tunable increased conductivity.

Researchers at NCCR MARVEL have combined first principles calculations with soft X-ray angle-resolved photoemission spectroscopy to examine tungsten diphosphide’s electronic structure, characterizing its Weyl nodes for the very first time. In agreement with density functional theory calculations, the results revealed two pairs of Weyl nodes lying at different binding energies. The observation of the Weyl nodes, as well as the tilted cone-like dispersions in the vicinity of the nodal points, provides compelling evidence that the material is a robust type-II Weyl semimetal with broken Lorentz invariance. This is as MARVEL researchers predicted two years ago. The research has been published in Physical Review Letters as an Editor's Suggestion.