Highlights of PSI-FELLOW Collaborations resulting in Publications
SwissFEL team has demonstrated the generation of widely tunable two-color x-ray free-electron laser (FEL) pulses with unprecedented photon energy ratio between the two colors of about three (350 and 915 eV), in addition to a tunable time separation between the two pulses from negative time delays to up to 500 fs. These new capabilities open new opportunities to study ultrafast x-ray-induced energy transfer and relaxation processes in physics, chemistry, and biology.
A team of scientists from Paul Scherrer Institut and Oak Ridge National Laboratory review recent experimental studies of spin dynamics in the rare-earth perovskite materials. These compounds show unconventional magnetic excitations at low temperatures, including confined and deconfined spinons as well as multimagnon states, which were revealed by means of high-resolution neutron spectroscopy. These observations demonstrate that the rare-earth perovskite magnets can provide realizations of various aspects of quantum low-dimensional physics.
In an exciting collaboration, Nick Phillips, a PSI Fellow at the cSAXS beamline, reveals nanoscale lattice distortions created by invisible defects in fusion reactor armor. This work develops the current understanding of how the smallest, but most prevalent defects, generated during neutron irradiation behave. The novel Bragg ptychographic approach published in Nature Communications paves the way for fast, robust, 3D Bragg ptychography.
A team of scientists from Konstanz have developed and characterized micrometre-size binary mesocrystals made from the self-assembly of ironoxide and platinum nanocubes and published their work in Angewandte Chemie International Edition. In collaboration with researchers from Empa and PSI, they used brilliant x-rays at the cSAXS beamline of the Swiss Light Source to characterize the lattice spacing in the crystalline structure of the mesocrystals and complement their results through electron microscopy.
Our collaborators at the Jozef Stefan Institute – the leading author, Jan Ravnik, is now a PSI Fellow at LMN – report a study of the electron ordering in equilateral triangle structures via photoexcitation of the prototypical dichalcogenide 1T-TaS2.
Our collaborators at the Jozef Stefan Institute – the leading author, Jan Ravnik, is now a PSI Fellow at LMN – report a ‘dynamical’ phase diagram of metastable quantum states generated via photoexcitation of the prototypical dichalcogenide material 1T-TaS2.
The authors demonstrate the stability of ferromagnetic order of one unit cell thick optimally doped manganite (La0.7Ba0.3MnO3, LBMO) epitaxially grown between two layers of SrRuO3 (SRO). LBMO shows ferromagnetism even above SRO Tc. Density Functional Theory calculations help understand the reasons behind this interesting result.
Chemical changes inside of breathable airborne particles can cause reactive oxygen species (ROS) and carbon centered radicals (CCRs) to form, which are harmful to our bodies and induce oxidative stress in lungs. Using X-ray spectromicroscopy at the PolLux beamline and mimicking the environmental and sunlit conditions aerosol particles experience in the atmosphere near the Earth Surface, it was recently found that highly viscous organic particles with low water content can attain high concentrations of ROS and CCRs that persist over long times. Natural particles like these will occur in ambient humidity below 60% and effectively trap ROS and CCRs inside that react when exposed to light.
Strontium ruthenate (Sr2RuO4) continues to present an important test of our understanding of unconventional superconductivity, because while its normal-state electronic structure is known with precision, its superconductivity remains unexplained. There is evidence that its order parameter is chiral, but reconciling this with recent observations of the spin part of the pairing requires an order parameter that is either finely tuned or implies a new form of pairing. Therefore, a definitive resolution of whether the superconductivity of Sr2RuO4 is chiral is important for the study of superconductivity.