Matter and Material

PSI researchers garner experience for SwissFEL experimentsAided by short laser flashes, researchers at the Paul Scherrer Institute have managed to temporarily change a material’s properties to such a degree that they have à to a certain extent àcreated a new material. This was done using the x-ray laser LCLS in California. Once the PSI x-ray laser SwissFEL is up and running, experiments of this kind will also be possible at PSI.

Researchers at the PSI, the EPFL and the Chinese Academy of Science, have proven that the material SmB₆ shows all the properties of a so called topological insulator à a material with electric currents flowing along its surface with all of them being polarized. Here, the property is very robust, i.e. the only current that can flow is spin polarized and is not easily destroyed by small irregularities in the structure or composition of the material. Spin polarized currents are necessary for spintronics, electronics using the electrons’ spin.

Processes in stars recreated with isotopes from PSIIsotopes that otherwise only naturally exist in exploding stars à supernovae à are formed at the Paul Scherrer Institute’s research facilities. This enables processes that take place inside the stars to be recreated in the lab. For instance, an international team of researchers used the titanium isotope Ti-44 to study one such process at CERN in Geneva. In doing so, it became evident that it is less effective than was previously believed and the previous theoretical calculations of processes in stars need to be corrected.

Researchers from ETH Zurich and the Paul Scherrer Institute PSI demonstrate how the magnetic structure can be altered quickly in novel materials. The effect could be used in efficient hard drives of the future.

Materials research, particle physics, molecular biology, archaeology à for the last forty years, the Paul Scherrer Institute’s large-scale proton accelerator has made top-flight research possible in a number of different fields.

Superconductivity and magnetic fields are normally seen as rivals à very strong magnetic fields normally destroy the superconducting state. Physicists at the Paul Scherrer Institute have now demonstrated that a novel superconducting state is only created in the material CeCoIn₅ when there are strong external magnetic fields. This state can then be manipulated by modifying the field direction. The material is already superconducting in weaker fields, too. In strong fields, however, an additional second superconducting state is created which means that there are two different superconducting states at the same time in the same material.

Above the transition temperature, some electrons in the superconducting material La_1.77Sr_0.23CuO₄ behave as if they were in a conventional metal, others as in an unconventional one à depending on the direction of their motion. This is the result of experiments performed at the SLS. The discovery of this anisotropy makes an important contribution towards understanding high-temperature superconductors. The effect will also have to be taken into account in future experiments and theories of high-temperature superconductors.

Researchers from the Paul Scherrer Institute have observed for the first time the extremely rare decay of the B_s meson into two muons. They have determined its decay frequency with sufficient accuracy using data collected by the CMS detector at CERN. Their result agrees with the predictions of the standard model of particle physics.

Understanding sodium dynamics on a microscopic levelLithium ion batteries are highly efficient, But there are drawbacks to the use of lithium: it is expensive and its extraction rather harmful to the environment. One possible alternative might be to substitute lithium with sodium. To be able to develop sodium-based batteries, it is crucial to understand how sodium ions move in the relevant materials. Now, for the first time, scientists at the Paul Scherrer Institute PSI have determined the paths along which sodium ions move in a prospective battery material. With these results, one can now start to think of new and specific ways to manipulate the materials through slight changes to their structure or composition, for example à and thereby achieve the optimized material properties necessary for use in future batteries.

Experiments conducted at the PSI have made it possible to determine how a unique Bronze Age axe was made. This was thanks to the process of neutron imaging, which can be used to generate an accurate three-dimensional image of an object’s interior. For the last decade, the PSI has been collaborating with various museums and archaeological institutions both in Switzerland and abroad. The fact that the 18th International Congress on Ancient Bronzes, which is to be held at the University of Zurich from 3 à 7 September, will also be meeting at the PSI for one day is a testament to the success of the cooperation.

A terahertz laser developed at the Paul Scherrer Institute makes it possible to control a material’s magnetisation precisely at a timescale of picoseconds. In their experiment, the researchers shone extremely short light pulses from the laser onto a magnetic material. The light pulse’s magnetic field was able to deflect the magnetic moments from their idle state in such a way that they exactly followed the change of the laser’s magnetic field with only a minor delay. The terahertz laser used in the experiment is one of the strongest of its kind in the world.

Researchers from the Paul Scherrer Institute (PSI) have made thin, crystalline layers of the material LuMnO₃ that are both ferromagnetic and antiferromagnetic at the same time. The LuMnO₃ layer is ferromagnetic close to the interface with the carrier crystal. As the distance increases, however, it assumes the material’s normal antiferromagnetic order while the ferromagnetism steadily becomes weaker. The possibility of producing two different magnetic orders within a material could be of major technical importance.

Highly sensitive processes take place in the cleanrooms of the Paul Scherrer Institute (PSI) as a single dust particle in the wrong place could have disastrous consequences. Here is a glimpse behind the scenes in rooms that are so clean even pencils are prohibited.

“Higgs Particle Found” announced the media triumphantly in July 2012. But for Roland Horisberger, particle physicist at PSI, this was a premature conclusion: “It will take at least another five years before we can be sure of that”. Whatever the findings à whether this is the original Higgs boson, or only one of the theoretical “Higgs-like” particles à one can surely put a tag on them that reads “PSI inside.”

Muons à unstable elementary particles à provide scientists with important insights into the structure of matter. They provide information about processes in modern materials, about the properties of elementary particles and the nature of our physical world. Many muon experiments are only possible at the Paul Scherrer Institute because of the unique intense muon beams available here.

Scientists use nano-rods to investigate how matter assemblesTo make the magnetic interactions between the atoms visible, scientists at the Paul Scherrer Institute PSI have developed a special model system. It is so big that it can be easily observed under an X-ray microscope, and mimics the tiniest movements in Nature. The model: rings made from six nanoscale magnetic rods, whose north and south poles attract each other. At room temperature, the magnetisation direction of each of these tiny rods varies spontaneously. Scientists were able to observe the magnetic interactions between these active rods in real time. These research results were published on May 5 in the journal “Nature Physics”.

Forscher des PSI und der ETH Zürich haben mit Kollegen vom Politecnico di Milano in der aktuellen Ausgabe der wissenschaftlichen Fachzeitschrift "Nature Photonics" eine Methode erarbeitet, einen Laser zu entwickeln, der schon bald in den neuesten Computern eingesetzt werden könnte. Damit könnte die Geschwindigkeit, mit der einzelne Prozessorkerne im Chip miteinander kommunizieren, drastisch erhöht werden. So würde die Leistung der Rechner weiter steigen.This news release is only available in German.

Prominent among the planned applications of X-ray free electron laser facilities, such as the future SwissFEL at the Paul Scherrer Institute, PSI, are structural studies of complex nano-particles, down to the scale of individual bio-molecules. A major challenge for such investigations is the mathematical reconstruction of the particle form from the measured scattering data. Researchers at PSI have now demonstrated an optimized mathematical procedure for treating such data, which yields a dramatically improved single-particle structural resolution. The procedure was successfully tested at the Swiss Light Source synchrotron at PSI.

Developmental Engineers from the firm LuK (D) wanted to see right through the metal housing of a clutch. They wanted to observe how the oil that lubricates and cools a clutch is distributed. A transparent disc becomes dirty very quickly, and X-rays merely reveal the metal. These engineers therefore turned to scientists at the Paul Scherrer Institute, who illuminated the metal with neutrons and thus made the lubricating oil visible. The results surprised everyone: only three of the eight lamellae were sufficiently lubricated.

Scientists at the Paul Scherrer Institute, together with Chinese and German collaborators, have obtained new insights into a class of high-temperature superconductors. The experimental results of this fundamental research study indicate that magnetic interactions are of central importance in the phenomenon of high-temperature superconductivity. This knowledge could help to develop superconductors with enhanced technical properties in the future.