Scientific Highlights
Low temperature activation of supported metathesis catalysts by organosilicon reducing agents
Industrial alkene metathesis processes rely on silica-supported tungsten oxide catalysts, which operate at high temperatures (>350 °C) due to the difficulty in generating active sites (carbenes or metallacyclobutanes). We report here a low temperature activation process of well-defined metal oxo surface species using organosilicon reductants, which generate a large amount of active species at only 70 °C (0.6 active sites/W).
Phononic Structure Engineering: the Realization of Einstein Rattling in Calcium Cobaltate for the Suppression of Thermal Conductivity
Phonons in condensed matter materials transmit energy through atomic lattices as coherent vibrational waves. Like electronic and photonic properties, an improved understanding of phononic properties is essential for the development of functional materials, including thermoelectric materials. Recently, an Einstein rattling mode was found in thermoelectric material Na0.8CoO2, due to the large displacement of Na between the [CoO2] layers.
Physical realization of a quantum spin liquid based on a complex frustration mechanism
Unlike conventional magnets where the magnetic moments are partially or completely static in the ground state, in a quantum spin liquid they remain in collective motion down to the lowest temperatures. The importance of this state is that it is coherent and highly entangled without breaking local symmetries.
Iridates from the molecular side
New exotic phenomena have recently been discovered in oxides of paramagnetic Ir4+ ions, widely known as ‘iridates’. Their remarkable properties originate from concerted effects of the crystal field, magnetic interactions and strong spin-orbit coupling, characteristic of 5d metal ions.
A Mini-Antenna for the Data Processing of Tomorrow
The use of spin-wave signals in future information processing devices can substantially reduce power consumption over present charge current based technologies. As part of an international research venture, scientists at PSI now introduced a concept to generate spin waves with nanoscale wavelengths exploiting the driven dynamics of magnetic vortex cores in magnetic heterostructures.
Magnesium Oxide Boosts the Hysteresis of Single-Molecule Magnets
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.
POLAR detector developed at the PSI flies into orbit with a Chinese space mission
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.
Shedding light on the origins of high-Tc superconductivity in bismuth oxides
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.
Muon polarization in the MEG experiment: predictions and measurements
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.
Ferromagnetic Quantum Critical Point Avoided by the Appearance of Another Magnetic Phase in LaCrGe3 under Pressure
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, AFMQ.