New material with magnetic shape memory

Researchers at the Paul Scherrer Institute PSI and ETH Zurich have developed a new material whose shape memory is activated by magnetism.

It retains a given shape when it is put into a magnetic field. It is a composite material consisting of two components. What is special about the new material is that, unlike previous shape-memory materials, it consists of a polymer and droplets of a so-called magnetorheological fluid embedded in it. Areas of application for this new type of composite material include medicine, aerospace, electronics and robotics. The researchers are now publishing their results in the scientific journal Advanced Materials.
It looks like a magic trick: A magnet moves away from a black, twisted band and the band relaxes –without any further effect (see video). What looks like magic can be explained by magnetism. The black ribbon consists of a composite of two components: a silicone-based polymer and small droplets of water and glycerine in which tiny particles of carbonyl iron float. The latter provide the magnetic properties of the material and its shape memory. If the composite material is forced into a certain shape with tweezers and then exposed to a magnetic field, this shape is retained even when the tweezers are removed. Only when the magnetic field is also removed does the material return to its original shape.

>Read more on the Swiss Light Source website

Image: Paolo Testa, first author of the study, with a model of the overall structure of the shape-memory material
Credit: Paul Scherrer Institute/Mahir Dzambegovic

New material also reveals new quasiparticles

Researchers at PSI have investigated a novel crystalline material that exhibits electronic properties that have never been seen before.

It is a crystal of aluminum and platinum atoms arranged in a special way. In the symmetrically repeating unit cells of this crystal, individual atoms were offset from each other in such a way that they – as connected in the mind’s eye – followed the shape of a spiral staircase. This resulted in novel properties of electronic behaviour for the crystal as a whole, including so-called Rarita-Schwinger fermions in its interior and very long and quadruple topological Fermi arcs on its surface. The researchers have now published their results in the journal Nature Physics.

Researchers at the Paul Scherrer Institute PSI have found a new kind of quasiparticle. Quasiparticles are states in material that behave in a certain way like actual elementary particles. The two physicists William Rarita and Julian Schwinger had predicted this type of quasiparticles in 1941, which came to be known as Rarita-Schwinger fermions. Exactly these have now been detected experimentally for the first time – thanks in part to measurements at the Swiss Synchrotron Light Source SLS at PSI. “As far as we know, we are – simultaneously with three other research groups – among the first to see Rarita-Schwinger fermions”, says Niels Schröter, a researcher at PSI and first author of the new study.

>Read more on the Swiss Light Source at PSI website.

Image: Niels Schröter (left) and Vladimir Strocov at their experimental station in the Swiss Light Source SLS at PSI.
Credit: Paul Scherrer Institute/Mahir Dzambegovic

A compass pointing West

Researchers at the Paul Scherrer Institute PSI and ETH Zurich have discovered a special phenomenon of magnetism in the nano range.

It enables magnets to be assembled in unusual configurations. This could be used to build computer memories and switches to increase the performance of microprocessors. The results of the work have now been published in the journal Science.
Magnets are characterized by the fact that they have a North pole and a South pole. If two common magnets are held close to each other, opposite poles attract and like poles repel each other. This is why magnetic needles, such as those found in a compass, align themselves in the Earth’s magnetic field so that we can use them to determine the cardinal directions North and South and, derived from this, East and West. In the world that we experience every day with our senses, this rule is correct. However, if you leave the macroscopic world and dive into depths of much smaller dimensions, this changes. Researchers at the Paul Scherrer Institute PSI and the ETH Zurich have now discovered a very special magnetic interaction at the level of nanoscopic structures made of magnetic layers only a few atoms thick.

>Read more on the Swiss Light Source at PSI website

Image: Zhaochu Luo, lead author of the study, in front of a so-called sputter deposition tool. In the apparatus the layers of platinum, cobalt and aluminium oxide are produced. Each layer is only a few nanometers thick. Credit: Paul Scherrer Institute/Mahir Dzambegovic

Virtual lens improves X-ray microscopy

PSI researchers are first to transfer state-of-the-art microscopy method to X-ray imaging

X-rays provide unique insights into the interior of materials, tissues, and cells. Researchers at the Paul Scherrer Institute PSI have developed a new method that makes X-ray images even better: The resolution is higher and allows more precise inferences about the properties of materials. To accomplish this, the researchers moved the lens of an X-ray microscope and recorded a number of individual images to generate, with the help of computer algorithms, the actual picture. In doing so they have, for the first time ever, transferred the principle of so-called Fourier ptychography to X-ray measurements. The results of their work, carried out at the Swiss Light Source SLS, are published in the journal Science Advances.

>Read more on the Swiss Light Source at PSI website

Image: Klaus Wakonig and Ana Diaz, together with other PSI researchers, have transferred the principle of Fourier ptychography to X-ray microscopy for the first time ever.
Credit: Paul Scherrer Institute/Markus Fischer

Industrial collaboration

Fabia Gozzo made a beamline at the Swiss Light Source SLS of the Paul Scherrer Institute PSI into one of the world’s leading facilities and today she is making her knowledge available to industry with her spin-off.

In spring 2012 Fabia Gozzo faced an important decision: security or risk? After 12 years, she had resigned from her job at the Paul Scherrer Institute to move to Brussels with her family. Her husband had taken a post as vice president of a company. The two had previously agreed to emigrate if one of them got such a one-of-a-kind offer.

Fabia Gozzo was looking for a job too. Soon she had an offer for a position as laboratory head at a Brussels-based institute for nano- and microelectronics. The position would have been a comparable to the one she had held up to that point at PSI. Then I asked myself: For that, do I want to burden myself with the trouble of this big relocation?, Gozzo says today. She found the answer was no. And instead, she founded her own firm: Excelsus Structural Solutions.

She had long had the idea of offering her experience in the analysis of material structures, which she had gained at the Swiss Light Source SLS, to the pharmaceutical industry. With the synchrotron light, the smallest devation from the desired solid structure in drugs can be detected – so their effectiveness can be improved. Gozzo and PSI signed an agreement for regular commercial use of a beamline at SLS. Now all Gozzo needed was customers. She gave herself two years to see if it would all work out.

>Read more on the Swiss Light Source at PSI website

Image: Fabia Gozzo is CEO and founder of Excelsus Structural Solutions. 
Credit: Scanderbeg Sauer Photography

A day as a young scientist

Physics isn’t everyone’s favourite subject. At the iLab of the Paul Scherrer Institute PSI, students experience the material in a different way: with experiments instead of memorising formulas.

Beat Henrich likes to use the Big Bang to explain the benefits of spectrometry to his adolescent guests. We know that everything in our universe is constantly moving apart, he says to the 17 students at the experiment station of the school laboratory iLab, only because we can measure the light of other galaxies. But because not all processes in the universe can be explained by matter that generates or reflects light, Henrich continues, scientists are currently investigating the “dark matter”, the big mystery in the history of the universe’s origins. If you make a discovery there, the head of iLab concludes, you would be candidates for the Nobel Prize.Is there a future Nobel laureate sitting here? Or a future top researcher? Michael Portmann, a physics teacher at the cantonal high school Alpenquai in Lucerne, casts a glance at the students of his two classes with whom he travelled to PSI today. Naturally, it’s too soon to tell, says Portmann, who has taught physics for 15 years and knows of a just handful of his former students who went on to study his subject later. But here it does show who is open to research.

Image: The school laboratory iLab gives young people an insight into the world of research.
Credit: Paul Scherrer Institute/Markus Fischer

Cleaner diesel emissions

More effective control of diesel nitrogen oxides through dosed addition of ammonia

In diesel engines, the burning of the fuel releases nitrogen oxides (NOx), which are harmful to human health. The automobile industry therefore developed a technique that reduces these emissions: Gaseous ammonia is added to the exhaust and, prompted by a catalyst, reacts with the nitrogen oxides to produce harmless nitrogen and water. At low temperatures, however, this process does not yet work optimally. Now, for the first time, scientists at the Paul Scherrer Institute PSI have found a remedy which is based on observations at the molecular level: The precise amount of added ammonia needs to be varied depending on the temperature. With this knowledge, manufacturers can improve the effectiveness of their catalytic converters for diesel vehicles. The researchers have now published their findings in the journal Nature Catalysis.

>Read more on the Paul Scherrer Institute website

Image: At the X-ray beam line: Davide Ferri (left) and Maarten Nachtegaal at the SLS experimental station where they studied diesel catalysis.
Photo: Paul Scherrer Institute/Markus Fischer

PSI spin-off GratXray wins Swiss Technology Award 2017

The young company GratXray is developing a new method for early diagnosis of breast cancer.

he Swiss Technology Award is considered Switzerland’s most significant technology prize and annually honours the best technological developments and innovations with high market potential in each of three categories: Inventors, Start-ups, and Innovation Leaders. Swiss companies as well as projects that were developed in Switzerland are eligible to compete. The spin-off GratXray received the prize in the Inventors category, in which young Swiss start-ups as well as innnovative business ideas with high market potential can qualify. In a multi-step application procedure, GratXray won out over its competitors.

Read more on the PSI website.

Image: The Swiss Technology Award in the Inventors category goes to the PSI spin-off GratXray. Accepting the prize, from left to right: Marco Stampanoni, Zhentian Wang, Martin Stauber (CEO of GratXray), and Giorgio Travaglini (head of Technology Transfer at PSI). (Photo: Paul Scherrer Institute)

Magnetic structures take a new turn

The unexpected finding that in an ‘artificial spin ice’ magnetostatic energy can be transformed into directed rotation of magnetization provides fresh insights into such nano-patterned magnetic structures — and might enable novel applications in nanoscale devices.

Magnetism and rotation are intimately related. This connection can lead to surprising and non-intuitive effects, as first demonstrated a century ago, when it was predicted, and observed, that changing the magnetization in a piece of ferromagnetic material (such as iron) rotates it, ever so slightly; conversely, spinning a non-magnetised piece of the same material magnetizes it. These phenomena are known as Einstein—de Haas and Barnett effects, respectively, and are beautiful phenomena described in many physics textbooks. Now, Sebastian Gliga and colleagues in the Laboratory for Multiscale Materials Experiments at PSI, led by of Laura Heyderman, report in Nature Materials [1] the discovery of another sort of rotation in a magnetic structure, one that came as a surprise. They observed that after magnetising their sample, the magnetisation started to consistently rotate in one of two possible directions, without an obvious reason why one way should be preferred over the other.

Read more on the PSI website

Time – and spatially – resolved magnetization dynamics driven by spin-orbit torques

There is a strong correlation between the rise of a civilization and writing. The so-called Information Age developed in parallel with the ability to write, store, and process large amounts of digital data. To keep pace with the increasing demand for data of our days, not only the size but also the speed of digital memories must increase dramatically, while keeping the energy consumption at reasonable levels. In order to achieve that, we must learn to write anew.

>Read More on the PSI website

Image: Magnetisation switching of a 500 nm diameter Pt/Co/AlOx disc.

Making the world go round

A look into the structure of a prominent heterogeneous catalyst

Fluid catalytic cracking, a century old chemical conversion process utilizing porous composites of zeolite and clay, up to this day provides the majority of the world’s gasoline. Owing to harsh reaction environments and feedstock impurities the employed catalysts deactivate, necessitating their continuous fractional replacement with major refineries requiring up to 40 tons of fresh catalyst in total on a daily basis. Using a combination of ptychographic, x-ray diffraction and -fluorescence tomography researchers from PSI and ETH elucidated the structural changes behind catalyst deactivation.

Read more on the PSI website.

Image: Cropped – Ptychographic image reconstructions. a Volume reconstructions of FCC1, FCC2, and FCC3. Orthoslices through the retrieved electron density maps are shown in b–d, respectively. Presented are bottom up (z–x) and orthogonal views (y–z, y–x). Cutting planes are represented by dotted lines. Shown in e–g are enlarged versions of selected areas. Common to all subfigures is the linear grey scale for the electron density. Selected diffusion highways (-) are highlighted in pink, hydrocarbon deposits by a red triangle, and the ASA shell by a blue cross. Voxel size is about (20 nm)3. Scale bars are 5 µm

Highly Crystalline C8-BTBT Thin-Film Transistors by Lateral Homo-Epitaxial Growth on Printed Templates

The latest generation of organic semiconductors display excellent characteristics, with charge mobilities surpassing those of amorphous silicon thin film transistors (TFTs) that are commonly used in today’s flat panel displays. The integration of organic TFTs (OTFTs) into real applications requires high performance and low spread of the electrical characteristics. As transport properties are greatly influenced by the microstructure of the organic layer, single crystalline films offer the greatest potential for high-performance OTFTs.

Read more on the PSI website.

Image: Schematic illustration of lateral homo-epitaxial growth in which well-ordered zone-cast material provides a template for further deposited molecules.

Atmosphere in X-ray light

Light from the particle accelerator helps to understand ozone decomposition

A new experimental chamber coupled to the Swiss Light Source (SLS), a large-scale research facility of the Paul Scherrer Institute PSI, allows researchers to recreate atmospheric processes in the laboratory through unprecedented precision analysis involving X-rays.

In their first experiments, researchers detailed how bromine molecules are formed in the air. These play an essential role in the decomposition of ozone in the lower layers of the atmosphere. With their results, the researchers have also made an important contribution to models designed to explain and predict changes in climate and air composition. In the future, the experimental setup will be available to researchers in all scientific fields and those particularly concerned with the chemistry of the atmosphere or other topics in energy and environmental research.

>Read More on the PSI website

Image: In the experimental chamber, a very thin vertical jet of water can be seen, which flows downward in the middle of the picture from a small tube. During the experiment, the chamber contains a gas mixture including ozone, which reacts on the surface with bromide in the water and produces bromine. As an intermediate step in the process, a short-lived compound of bromide and ozone is made, which was detected for the first time ever with the help of X-ray light from SLS. For this proof, the X-ray light knocked electrons out of the compound, and these made their way to the detector through an opening in the cone (to the left in this photo). (Photo: Paul Scherrer Institute/Mahir Dzambegovic)

Diving into magnets

First-time 3D imaging of internal magnetic patterns

Magnets are found in motors, in energy production and in data storage. A deeper understanding of the basic properties of magnetic materials could therefore impact our everyday technology. A study by scientists at the Paul Scherrer Institute PSI in Switzerland, the ETH Zurich and the University of Glasgow has the potential to further this understanding.

The researchers have for the first time made visible the directions of the magnetisation inside an object thicker than ever before in 3D and down to details ten thousand times smaller than a millimetre (100 nanometres). They were able to map the three dimensional arrangement of the magnetic moments. These can be thought of as tiny magnetic compass needles inside the material that collectively define its magnetic structure. The scientists achieved their visualisation inside a gadolinium-cobalt magnet using an experimental imaging technique called hard X-ray magnetic tomography which was developed at PSI. The result revealed intriguing intertwining patterns and, within them, so-called Bloch points.

At a Bloch point, the magnetic needles abruptly change their direction. Bloch points were predicted theoretically in 1965 but have only now been observed directly with these new measurements. The researchers published their study in the renowned scientific journal Nature.

>Read More on the PSI website

Image: A vertical slice of the internal magnetic structure of a sample section. The sample is 0.005 millimetres (5 micrometres) in diameter and the section shown here is 0.0036 millimetres (3.6 micrometres) high. The internal magnetic structure is represented by arrows for a vertical slice within it. In addition, the colour of the arrows indicate whether they are pointing towards (orange) or away from the viewer (purple). (Graphics: Paul Scherrer Institute/Claire Donnelly)

Photonic structure of white beetle wing scales: optimized by evolution

They have developed a complicated three-dimensional photonic structure on their wing scales in order to efficiently reflect white light.

At the same time, this structure is very porous and is confined within a thin layer of about 10  µm, about one fifth of the thickness of ordinary white paper, which makes it very light and therefore advantageous to fly.

Researchers of the University of Fribourg and their collaborators wanted to understand how this fascinating structure is optimized, for which they needed a faithful 3D image. However, conventional microscopy techniques providing enough spatial resolution such as electron microscopy required the sample to be cut for imaging consecutive slices, causing damage of the structure during the process.

>Read More on the PSI website

Image: Cyphochilus white beetle source: PSI