Data Science

Researchers from PSI and EPFL have demonstrated that the magnetization hysteresis and remanence of TbPc₂ single-molecule magnets drastically depends on the substrate on which they are deposited. If a few atomic layers thick magnesium oxide film grown on a silver substrate is used, a record wide hysteresis and record large remanence can be obtained. Single-molecule magnets are attractive for molecular spintronics applications such as information processing or storage.

Researchers working with Wojciech Hajdas at the Paul Scherrer Institute PSI have developed a detector called POLAR. This instrument is expected to search out and investigate so-called gamma ray bursts coming from the depths of the universe. Gamma ray bursts are eruptions of high-energy light that despite being extremely strong remain, up to now, only poorly understood.

Researchers have overcome a number of challenges in order to employ an advanced probe in the study of an unusual material, barium bismuth oxide (BaBiO3) – an insulating parent compound of a family of high-temperature superconductors known since the late 80s. In order to finally realize the experiments, the researchers grew and studied thin films of the material completely in situ under ultrahigh vacuum conditions. The results show that superconductivity in bismuth oxides emerges out of a novel insulating phase, where hole pairs located on combinations of the oxygen orbitals are coupled with distortions of the crystal lattice.

The temperature-pressure phase diagram of the ferromagnet LaCrGe₃ is determined for the first time from a combination of magnetization, muon-spin-rotation, and electrical resistivity measurements. The ferromagnetic phase is suppressed near 2.1 GPa, but quantum criticality is avoided by the appearance of a magnetic phase, likely modulated, AFM_Q.

The MEG experiment makes use of one of the world’s most intense low energy muon beams, in order to search for the lepton flavour violating process μ+→e+γ . We determined the residual beam polarization at the thin stopping target, by measuring the asymmetry of the angular distribution of Michel decay positrons as a function of energy. The initial muon beam polarization at the production is predicted to be Pμ=−1Pμ=−1 by the Standard Model (SM) with massless neutrinos.

We investigate the band structure of BaBiO₃, an insulating parent compound of doped high-T_c superconductors, using in situ angle-resolved photoemission spectroscopy on thin films. The data compare favorably overall with density functional theory calculations within the local density approximation, demonstrating that electron correlations are weak. The bands exhibit Brillouin zone folding consistent with known BiO₆ breathing distortions.

A promising system for painless and minimally-invasive therapeutic drug monitoring has been demonstrated. The proposed device combines biofunctionalized hollow microneedles with an optofluidic system to measure drug concentrations in volumes as small as 0.6 nL.

X-ray magnetic circular dichroism at the Co L_3,2 edges measured at the X-Treme beamline, SLS and at the Advanced Light Source, evidence that three distinct electric field driven remanent magnetization states can be set in the Co film at room temperature. Ab initio density functional theory calculations unravel the relative contributions of both strain and charge to the observed magnetic anisotropy changes illustrating magnetoelectroelastic coupling at artificial multiferroic interfaces.

A method to precisely alter the quantum mechanical states of electrons within an array of quantum boxes has been developped by an international consortium also including PSI. The method can be used to investigate the interactions between various types of atoms and electrons, which is essential for future quantum technologies.

Researchers at the Paul Scherrer Institute's Swiss Light Source in Villigen, Switzerland, have developed an X-ray grating interferometry setup which does not require an analyzer grating, by directly detecting the fringes generated by the phase grating with a high resolution detector. The 25um pitch GOTTHARD microstrip detector utilizes a direct conversion sensor in which the charge generated from a single absorbed photon is collected by more than one channel. Therefore it is possible to interpolate to achieve a position resolution finer than the strip pitch.

Resonant magnetic scattering performed at the x-ray free electron laser facility LCLS (USA) has been used to investigate the magnetization dynamics of elemental Holmium. It is found that the demagnetization of conduction electrons and localized 4f magnetic moments have the same temporal evolution showing a strong coupling between the different magnetic moments.

The SwissFEL Experimental Laser 1 has successfully been delivered and installed in a temporary laser lab by Coherent, from where it will be moved to SwissFEL by end of 2016. The pre-installation in the temporary laser lab allows to become acquainted with the system, to set up a full monitoring and diagnostics system and to debug potential problems in the next months.

The key to achieving more effective radioprotection and radiotherapy is to understand the exact mechanism of the interaction between radiation and biomolecules, and in particular to obtain the precise structure of the different forms of damage and their relative ratios. Among all biomolecules exposed to radiation, DNA plays an important role because any damage to its molecular structure can affect the whole cell and may lead to chromosomal rearrangements resulting in genomic instability or cell death.

Centrioles are fundamental and evolutionarily conserved microtubule-based organelles whose assembly is characterized by microtubule growth rates that are orders of magnitude slower than those of cytoplasmic microtubules. Here, we bring together crystallographic, biophysical, and reconstitution assays to demonstrate that the human centriolar protein CPAP (SAS-4 in worms and flies) binds and "caps" microtubule plus ends by associating with a site of β-tubulin engaged in longitudinal tubulin-tubulin interactions.

We report ac susceptibility, specific heat, and neutron scattering measurements on a dipolar-coupled antiferromagnet LiYbF₄. For the thermal transition, the order-parameter critical exponent is found to be 0.20(1) and the specific-heat critical exponent −0.25(1). The exponents agree with the 2D XY/h₄ universality class despite the lack of apparent two-dimensionality in the structure.

A. Scotti et al., Proceedings of the National Academy of Sciences, 1516011113 (2016). Understanding when a material crystallizes is of fundamental importance in condensed matter. In many materials, the presence of point defects suppresses crystallization. Surprisingly, colloidal hydrogels can overcome this limitation: A small number of large microgels can spontaneously deswell to fit in the crystal lattice of smaller microgels, thus avoiding the occurrence of point defects.

The answer to this question could save food industry a lot of money and reduce food waste caused by faulty production. Researchers from the University of Copenhagen and the Paul Scherrer Institut have obtained a 3D image of food on the nanoscale using ptychographic X-ray computed tomography. This work paves the way towards a more detailed knowledge of the structure of complex food systems.