Scientific Highlights
Operando X-ray diffraction during laser 3D printing
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.
Characterisation of work hardening and springback in Ti
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.
Ultrafast Transient Increase of Oxygen Octahedral Rotations in a Perovskite
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.
Research and tinkering – SwissFEL in 2019
The newest large research facility at the Paul Scherrer Institute, SwissFEL, has been completed. In January 2019 it began regular operation. Henrik Lemke, head of the SwissFEL Bernina research group, gives an interim report.
Weyl fermions discovered in another class of materials
A particular variety of particles, the so-called Weyl fermions, had previously only been detected in certain non-magnetic materials. But now researchers at PSI have experimentally proved their existence for the first time in a specific paramagnetic material.
PSI School for Master Degree Students - Introducing Photons, Neutrons and Muons for Condensed Matter Physics and Materials Science
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
New material also reveals new quasiparticles
Researchers at PSI have investigated a novel crystalline material at the Swiss Light Source SLS that exhibits electronic properties never seen before. Among other things, they were able to detect a new type of quasiparticle: so-called Rarita-Schwinger fermions.
An iodine polymeric chain with tunable conductivity
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.
New study gives compelling evidence that tungsten diphosphide is a type-II Weyl semimetal
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.