Transition énergétique

The geometry of magnetic flux penetration in a high temperature superconductor at a buried interface was imaged using element-specific x-ray excited luminescence. We performed low tem- perature observation of the flux penetration in YBa₂Cu₃O_7–δ (YBCO) at a buried interface by imaging of the perpendicular magnetization component in square Permalloy (Py) mesostructures patterned superjacent to a YBCO film.

Our experiments, published in the September issue of Structural Dynamics, demonstrate the feasibility of time-resolved pump-multiprobe X-ray diffraction experiments on protein crystals using a split-and-delay setup which was temporarily installed at the LCLS X-ray Free Electron Laser.

Carbonate minerals serve as reservoir for CO2 in the global CO2 cycle, as biomineral in animal skeletons and shells of marine animals, and are used in carbon capturing techniques. Moreover, they serve as an important model system in crystallization studies, and have important commercial applications, for example as fillers. Researchers from EPFL and PSI developed a new methodology to study the crystallization of CaCO3 that offers both high temporal and spatial resolution, which is the key challenge in elucidating early stages of crystallization. Using X-ray absorption spectroscopy and other techniques it could be demonstrated that the degree of hydration of amorphous CaCO3 increases during its growth. As a result of the increasing degree of hydration, the stability of the resulting amorphous particles against solid-state crystallization decreases.

Spent fuel management is becoming one of the major concerns in many countries with a nuclear program. The radiation aspect as well as the safe and economical part of the long-term storage of the spent nuclear fuel has to be evaluated with a high degree of confidence. To assist such project from the neutronic simulation side, a new method is proposed to systematically calculate at the same time canister loading curves and radiation sources, based on the inventory information from an in-core fuel management system.

Using soft x-ray angle-resolved photoemission spectroscopy we probed the bulk electronic structure of T_d-MoTe₂. We found that on-site Coulomb interaction leads to a Lifshitz transition, which is essential for a precise description of the electronic structure. A hybrid Weyl semimetal state with a pair of energy bands touching at both type-I and type-II Weyl nodes is indicated by comparing the experimental data with theoretical calculations.

Despite the apparent simplicity of pulsed laser deposition, consistent deposition of thin films with the desired thickness, composition, crystallinity, and quality still remains challenging. This article explores the influence of process parameters with respect to film thickness and composition, two key aspects for thin films which have a very strong effect on film properties, possible applications, and characterization.

Despite the apparent simplicity of pulsed laser deposition, consistent deposition of thin films with the desired thickness, composition, crystallinity, and quality still remains challenging. This article explores the influence of process parameters with respect to film thickness and composition, two key aspects for thin films which have a very strong effect on film properties, possible applications, and characterization.

The summer shutdown was used to install more missing hardware. With the new components the Bernina instrument will be already very close to the full design capabilities when the exciting time of user experiments will begin in 2019.

The Mermin–Wagner theorem has long told us that in two dimensions a continuous symmetry can be broken, allowing a finite order parameter, only at zero temperature. Now PSI theorist Bruce Normand, working with colleagues in Aachen, Amsterdam, Lausanne and Paris, has circumvented this rule. The team was considering the thermodynamics

We consider the finite-temperature phase diagram of the S=1/2 frustrated Heisenberg bilayer. Although this two-dimensional system may show magnetic order only at zero temperature, we demonstrate the presence of a line of finite-temperature critical points related to the line of first-order transitions between the dimer-singlet and -triplet regimes.

Magnetic skyrmions are vortex-like topological spin textures often observed to form a triangular-lattice skyrmion crystal in structurally chiral magnets with the Dzyaloshinskii-Moriya interaction. Recently, β-Mn structure-type Co-Zn-Mn alloys were identified as a new class of chiral magnet to host such skyrmion crystal phases, while β-Mn itself is known as hosting an elemental geometrically frustrated spin liquid.

The demonstration that applied pressure can substantially change – rather than merely tweak – the properties of a metal–organic quantum magnet indicates a route to designing quantum materials with tailored properties.

At this year's annual meeting of the Swiss Nanoscience Institute (SNI) Jens Gobrecht, the former Head of LMN, received the SNI Honorary Membership.

Solid deuterium (sD₂) is used as an efficient converter to produce ultracold neutrons (UCN). Itis known that the sD₂ must be sufficiently cold, of high purity and mostly in its ortho-state in order to guarantee long lifetimes of UCN in the solid from which they are extracted into vacuum.

We report an extraordinary pressure dependence of the magnetic interactions in the metal-organic system [CuF₂(H₂O)₂]₂ pyrazine. At zero pressure, this material realizes a quasi-two-dimensional spin-1/2 square-lattice Heisenberg antiferromagnet. By high-pressure, high-field susceptibility measurements we show that the dominant exchange parameter is reduced continuously by a factor of 2 on compression.