Category: Swiss Light Source (SLS)

The Cables of the SLS

The Cables of the SLS

Knowing the paths that cables take also means knowing the machine to which they belong. Emanuel Hüsler, Head of the Electrical Installations Section at the Paul Scherrer Institute PSI, guides us through the complex electrical network of SLS 2.0 and thereby through the entire upgrade.

Network cables, high-voltage cables, supply cables, power cables, fibre optic cables – the cables installed in recent months by the Electrical Installations Section, headed by Emanuel Hüsler, come in a wide variety of shapes and colours. Research at the Swiss Light Source SLS at PSI has been on hold since the end of September 2023: The SLS 2.0 upgrade is in full swing and will allow the refurbished facility to produce even more brilliant synchrotron light for scientific experiments, starting in 2025. As part of this upgrade, Hüsler and his team have already laid 30,000 cables, whose total length of 504 kilometres would theoretically allow someone to abseil from the International Space Station (ISS) to Earth.

A strict numbering scheme ensures that the many cables do not end up as a hopeless tangle of wires. Each cable is recorded in layouts of the system as well as in lists; each is labelled and installed chronologically under raised floors, in rails or in cabinets. “Our professional pride dictates meticulous workmanship, which is also helpful later on, when the system goes into operation,” says Hüsler.

The qualified electrician takes major projects like the SLS upgrade in his stride. He joined PSI as group leader in 2007, having previously gathered many years of experience in industry and trained as a Swiss certified electrician (advanced diploma). In 2014, he took over as Head of the Electrical Installations Section, which is part of the PSI Centre for Accelerator Science and Engineering.

Read more on the PSI website

Image: Some 30,000 cables with a total length of 504 kilometres wind their way through the complex large research facility of the SLS.

Credit: © Paul Scherrer Institute PSI/Markus Fischer

IMPACT: Upgrade at PSI research facility approved

IMPACT: Upgrade at PSI research facility approved

Green light for IMPACT: The upgrade at the proton accelerator facility at the Paul Scherrer Institute PSI planned for the coming years will be implemented. Funding for this two-part enhancement was assured within the framework of the ERI Dispatch 2025-2028.

Financing of the Swiss Dispatch on promotion of Education, Research, and Innovation (ERI) in the years 2025 through 2028 was approved in mid-December 2024 in the Swiss Parliament. This means the budget that the ETH Domain is to receive for the coming years has been approved. This budget includes 50 million Swiss francs with which the ETH Council will co-finance the IMPACT project from central funds in the period 2025-2028. The upgrade to the user facilities associated with the proton accelerator at the Paul Scherrer Institute PSI can thus be realised.

IMPACT is a joint project of PSI, the University of Zurich, and the University Hospital of Zurich. It comprises two significant upgrades to PSI’s research facilities: 

First, under the name HIMB, two beamlines for experiments with muons will be significantly improved. Muons are secondary particles generated by the protons. HIMB will increase by a factor of 100 the number of muons used for research purposes, for example in physics and materials science.

Second, a new facility called TATTOOS will be built, where important radionuclides can be produced. Radionuclides are used to produce radiopharmaceuticals, which in turn are used to diagnose and treat cancer.

“We are very pleased that funding for IMPACT has been approved as part of the ERI dispatch,” says PSI Director Christian Rüegg. “We are proud and grateful that we can continue to invest in the future. Education and research secure the prosperity and independence of Switzerland,” continues Rüegg. “Especially in financially difficult times, we therefore need strong research and innovation and strategic, forward-looking investments. IMPACT is an important step for the future of materials research, medicine and particle physics.”

Read more on the PSI website

Image: PSI Director Christian Rüegg at the cover of the cyclotron, which represents the third acceleration stage for the proton beam at PSI, which is unique worldwide.

Credit: © Scanderbeg Sauer Photography

Mapping the Nanoscale Architecture of Functional Materials

Mapping the Nanoscale Architecture of Functional Materials

At the Swiss Light Source SLS, researchers have developed a pioneering X-ray technique to probe the 3D orientation of a material’s building blocks at the nanoscale. Applied to a polycrystalline catalyst, the technique allows the visualisation of crystal grains, grain boundaries and defects – key factors dictating catalyst performance. Beyond catalysis, the innovation unlocks previously inaccessible details about the structure of diverse functional materials, including those used in information technology, energy storage and biomedical applications. The findings are reported in Nature. 

Zoom in to the micro or nanostructure of functional materials, both natural and manmade, and you’ll find they consist of thousands upon thousands of coherent domains or grains – distinct regions where molecules and atoms are arranged in a repeating pattern. 

Such local ordering is inextricably linked to the material properties. The size, orientation, and distribution of grains can make the difference between a sturdy brick or a crumbling stone; it determines the ductility of metal, the efficiency of electron transfer in a semiconductor, or the thermal conductivity of ceramics. It is also an important feature of biological materials: collagen fibres, for example, are formed from a network of fibrils and their organisation determines the biomechanical performance of connective tissue. 

These domains are often tiny: tens of nanometres in size. And it is their arrangement in three-dimensions over extended volumes that is property-determining. Yet until now, techniques to probe the organisation of materials at the nanoscale have largely been confined to two-dimensions or are destructive in nature. 

Now, using X-rays generated by the Swiss Light Source SLS, a collaborative team of researchers from Paul Scherrer Institute PSI, ETH Zurich, the University of Oxford and the Max Plank Institute for Chemical Physics of Solids have succeeded in creating an imaging technique to access this information in three-dimensions.

Read more on PSI website

Image: Many functional materials are composed of coherent domains or grains, where molecules and atoms are arranged in a repeating pattern that determines performance. X-ray Linear Dichroic Orientation Tomography (XL-DOT) allows 3D mapping of material microstructure at the nanoscale. Here, the technique is applied to a pillar of vanadium pentoxide catalyst, used in the production of sulfuric acid. The colours in the tomogram represent the different orientation of grains.

Credit: Paul Scherrer Institute PSI/Andreas Apseros

UK and Switzerland partner for science using neutrons, muons and X-rays

UK and Switzerland partner for science using neutrons, muons and X-rays

A strategic partnership between research facilities in the UK and Switzerland has been established by the UK International Science Partnerships Fund (ISPF), which will develop new capabilities for science using neutrons, muons and X-rays. 

UK facilities – ISIS Neutron and Muon Source (ISIS) and the Diamond Light Source, located at the Rutherford Appleton Laboratory (RAL) – and the Paul Scherrer Institute (PSI), in Switzerland – home to the Swiss Spallation Neutron Source SINQ, the Swiss Muon Source SµS, the Swiss Light Source SLS and the X-ray Free-Electron Laser SwissFEL, will create new scientific capabilities to address global challenges.  

These large-scale research infrastructures have a rich history in pushing forward science in key areas for our society, such as net zero technology development, healthcare solutions and therapies, and resilient communications, relying on their ability to study material properties at the atomic and molecular scales. Recent studies have included investigation of materials for enhanced batteries, quantum computing and technologies, and novel drug delivery mechanisms, as well as fundamental science investigations. The ISPF partnership will enable new projects to be taken forward, developing capabilities for research facilities that benefit society overall. 

Researchers and technical teams from ISIS, Diamond and PSI have already worked in close collaboration for many years. The ISPF funding will allow an extension of collaborations into new research areas, enabling the development of novel capabilities in both countries. Around 16 projects will be taken forward as part of the programme, with 16 early-career postdoctoral researchers employed to work between the facilities. 

Read more on Diamond website

Image: Meeting of members of the ISIS – Diamond – PSI partnership at the Rutherford Appleton Laboratory, 27-28 November 2024.

Unlocking the secrets of proteins

Unlocking the secrets of proteins

This year’s Nobel Prize in Chemistry goes to three researchers who have made a decisive contribution to cracking the code of proteins – important building blocks of life. However, developing applications from this knowledge, for example in medicine, requires research institutes such as PSI. 

This year’s Nobel Prize in Chemistry came as a surprise in several respects. Firstly, only one of the three scientists chosen, David Baker, is a member of an academic research institution. The other two, Demis Hassabis and John Jumper, work at the Google subsidiary DeepMind. Secondly, the award is based on artificial intelligence (AI). And thirdly, the achievement being recognised draws on an Open Science project that would not have been possible without comprehensive, high-quality, open databases provided by the global scientific community – to which the Paul Scherrer Institute PSI is an important contributor. Given these unusual circumstances, it is easy to overlook the actual reason for awarding the prize. Yet that itself is revolutionary enough: The Nobel Committee is paying tribute to the three scientists for a breakthrough in protein research. Working at the company DeepMind, two of them developed an AI called AlphaFold which is able to predict the spatial structure of a protein with astonishing precision. This structure is a result of the way the molecule is folded, which in turn depends on the sequence of amino acids it contains.

Spatial folding is crucial

It is difficult to assess the full extent of the new possibilities offered by AlphaFold. Proteins and their spatial folding form the central basis of all biological systems – disrupting them can have fatal consequences. The form, function and activity of every single cell are controlled by proteins. This also holds true for the 30 trillion or more cells that make up the human body, or course, including the cells of the immune system and the brain, but also pathologically modified cancer cells. Some extra-cellular structures produced by cells are also made from proteins. These include collagen, which gives skin, bones, tendons and connective tissue their structure and strength. However, until recently scientists were often puzzled as to how the sequence of amino acids, which is relatively easy to determine, gives rise to the three-dimensional configuration.

To determine the spatial structure of proteins, which is crucial for their biological function, researchers had to resort to highly complex X-ray crystallography experiments, which often took years. Only in recent years has it become possible to achieve this by means of a particularly high-resolution form of electron microscopy. X-ray crystallography was first successfully used to determine the structure of a protein in 1959; the protein in question was myoglobin, the mussel protein which is responsible for intramuscular oxygen transport. The scientists led by Max Perutz, who was awarded the Nobel Prize for Chemistry in 1962, turned the protein into a crystal and sent monochromatic X-rays through it, similar to the radiation produced by Swiss Light Source SLS at PSI. The resulting diffraction pattern can be used to determine the folding of the protein chain – and thus provide information about the function of the protein. The location of active centres, for example, which interact with small molecules. 

At the time that AlphaFold was developed, the structure of some 140,000 proteins had been determined experimentally. These are all listed in the Protein Data Bank (PDB), established in 1971, which is freely accessible to scientists and the general public. “More than five percent of the data it contains comes from the Swiss Light Source SLS at PSI,” says Jörg Standfuss, Head of the Laboratory of Biomolecular Research, which focuses on structural biology at the PSI Centre for Life Sciences. Most of the rest comes from other research centres that operate a high-quality X-ray source.

Read more on PSI website

Image: Proteins are involved in all life processes. They are made up of amino acid chains that form complex structures. This structure is crucial to the function of the proteins. That is why being able to predict the structure of a protein based on its amino acid sequence using AI is so important for understanding life and for innovation in medicine and biology.

Credit: hotspianiegra – stock.adobe.com

Artificial intelligence explores the underground

Artificial intelligence explores the underground

Researchers at the Paul Scherrer Institute PSI have shown that artificial neural networks have the potential to determine very precisely the characteristics of rock layers, like their mineralogical composition, solely on the basis of drill core images. This could speed up future geological investigation efforts while simultaneously optimising costs. 

Underground investigations are often time-consuming and costly. Yet without knowledge of the properties and characteristics of the layers located deep below the surface, many important questions cannot be answered: Can data for future explorations around the deep geological repository be predicted quickly and reliably? Is a particular underground site suitable for obtaining deep geothermal heat and power, or for extracting natural gas? Are the geological conditions at a depth of 1,500 metres suitable for storing carbon dioxide? To make it easier to answer these and other questions, Romana Boiger, from the Laboratory for Waste Management in the PSI Center for Nuclear Engineering and Sciences, is working to establish new tools from the area of artificial intelligence for geological investigations.

Boiger’s attention is focused on so-called artificial neural networks in particular. These consist of several layers of interconnected artificial neurons. These are, in the final analysis, mathematical formulas that process input data and deliver a result. What makes this special is that artificial neural networks are capable of learning. For example, an artificial neural network that is supposed to distinguish between apples and pears can be trained by presenting it with images of apples and pears and simultaneously providing the correct interpretation. After a certain number of training runs, the artificial neural network is then prepared to correctly classify even unfamiliar pictures of apples and pears.

In her research, Boiger, a mathematician with a focus on data science and machine learning, uses a special type of artificial neural networks called convolutional neural networks (CNNs). These are especially well suited to the identification and analysis of patterns and simple features in images.

Scientifically uncharted territory

One novel application of CNNs is the subject of the study Boiger and colleagues published in May 2024 in the Swiss Journal of Geosciences. It is the result of an interdisciplinary collaboration between scientists from PSI and experts in geology and engineering at Nagra. In a first step, they used CNNs to analyse images of drill cores taken from the Trüllikon borehole in Northern Switzerland. This was part of Nagra’s site investigation programme to identify a suitable site for a deep geological repository. The test interval was selected from 55 metres of drill core from a depth of between 770 and 939 metres. «We wanted to find out if it’s possible to accurately determine the lithological formations and above all the mineralogical composition of the rock – such as the proportions of calcite, clay, and silicates – solely on the basis of drill core images. » Studies already exist to investigate the lithology, determining properties that can be observed with the naked eye, without the help of a microscope. On the other hand, determining mineralogy in this way is scientifically uncharted territory. «No one had ever done it this way before.»

For her research, Boiger used artificial neural networks that had already been trained. They had previously learned to distinguish between images of vehicles, animals, people, and fruit – as well as geological formations and rocks – using images from the ImageNet database, a collection of more than 14 million images.

The CNN models thus already had a certain knowledge base when they were presented with the Trüllikon drill cores. The 10 cm thick drill cores from various geological units, known as formations, were systematically photographed after washing. The photographs were then cut into slices. Boiger and colleagues proceeded step by step: They expanded the pre-trained CNN by a few layers, which they then specifically trained to distinguish between lithological formations on the basis of the images. This resulted in a new, larger CNN model. It was then expanded again by a few layers – and finally trained to recognise the mineralogical composition.

Read more on PSI website

Image: Romana Boiger wants to use artificial intelligence to improve the exploration of deep earth layers and the analysis of drill cores.

Credit: Paul Scherrer Institute PSI/Markus Fischer

Excited About SLS 2.0!

Excited About SLS 2.0!

After 22 years of brilliant science, at 8am on the 30th of September 2023, the SLS went into temporary shutdown as the SLS 2.0 upgrade began. In the video series #ThankYouSLS, seven beamline scientists from PSI looked back on a few of the many discoveries made possible by light from the SLS. 

Now in a new video series #ExcitedAboutSLS, the same researchers tell us why they can’t wait for the SLS 2.0 upgrade. Across the diverse applications, stretching from molecular biology to quantum materials, the researchers look forward to faster experiments, higher resolution, and more realistic conditions. With this, the light of SLS 2.0 – and the thousands of scientists from around the world that use it – will address societal challenges such as health and the energy transition.

Read more on SLS website

New X-ray world record: Looking inside a microchip with 4 nanometre precision

New X-ray world record: Looking inside a microchip with 4 nanometre precision

n a collaboration with EPFL Lausanne, ETH Zurich and the University of Southern California researchers at the Paul Scherrer Institute PSI have used X-rays to look inside a microchip with higher precision than ever before. The image resolution of 4 nanometres marks a new world record. The high-resolution three-dimensional images of the type they produced will enable advances in both information technology and the life sciences. The researchers are reporting their findings in the current issue of the journal Nature.

Since 2010, the scientists at the Laboratory of Macromolecules and Bioimaging at PSI have been developing microscopy methods with the goal of producing three-dimensional images in the nanometre range. In their current research, a collaboration with the EPFL and the ETHZ, the Swiss Federal Institutes of Technology in Lausanne and Zürich, and the University of Southern California, they have succeeded for the first time in taking pictures of state-of-the-art computer chips microchips with a resolution of 4 nanometres, i.e. 4 millionths of a millimetre – a world record. Instead of using lenses, with which images in this range are not currently possible, the scientists resort to a technique known as ptychography, in which a computer combines many individual images to create a single, high-resolution picture. Shorter exposure times and an optimised algorithm were key to significantly improving upon the world record they themselves set in 2017. For their experiments, the researchers used X-rays from the Swiss Light Source SLS at PSI.

Between conventional X-ray tomography and electron microscopy

Microchips are marvels of technology. Nowadays, it is possible to pack more than 100 million transistors per square millimetre into advanced integrated circuits – a trend that continues to increase. Highly automated optical systems are used to etch the nanometre-sized circuit traces into silicon blanks in clean rooms. Layer after layer is added and removed until the finished chip, the brains of our smartphones and computers, can be cut out and installed. The manufacturing process is elaborate and complicated, and characterising and mapping the resulting structures proves to be just as difficult.

While scanning electron microscopes have a resolution of a few nanometres and are therefore well suited to imaging the tiny transistors and metal interconnects that make up circuits, they can only produce two-dimensional images of the surface. “The electrons don’t travel far enough into the material,” explains Mirko Holler, a physicist at SLS. “To construct three-dimensional images with this technique, the chip has to be examined layer by layer, removing individual layers at the nanometre level – a very complex and delicate process which also destroys the chip.”

However, three-dimensional and non-destructive images can be produced using X-ray tomography, because X-rays can penetrate materials much further. This procedure is similar to a CT scan in a hospital. The sample is rotated and X-rayed from different angles. The way the radiation is absorbed and scattered varies, depending on the internal structure of the sample. A detector records the light leaving the sample and an algorithm reconstructs the final 3D image from it. “Here we have a problem with the resolution,” explains Mirko Holler. “None of the X-ray lenses currently available can focus this radiation in a way that allows such tiny structures to be resolved.”

Read more om PSI website

Image: The sample, an extract from a commercial computer chip, is supported by the gold-coloured pin in the centre of the picture. Less than 0.000 005 metres in diameter (about 20 times smaller than the width of a human hair), it was cut out of the chip using a focused ion beam and placed on the pin.

Credit: Paul Scherrer Institute PSI/Mahir Dzambegovic

Fundamentally different

Fundamentally different

Large research facilities at PSI such as the X-ray free-electron laser SwissFEL and the Swiss Light Source SLS – especially after the upgrade SLS 2.0 – deliver unimaginably vast amounts of data. Artificial intelligence is helping to evaluate data efficiently and exploit the facilities’ full potential for research.

Proteins are the workhorses of life. As tiny molecular machines, they are found in every cell and have a role in nearly all biological processes – from metabolism to cellular communication. Their diversity is enormous, because in the human body alone there are hundreds of thousands of different proteins, each with its own function. Proteins are important targets for drugs, and understanding their structure and function is an important task in biological research. One challenge in drug development is to find, if possible, an active agent that interacts with just one type of protein, to the exclusion of all the rest.

To achieve such a feat, one must first understand the language of proteins. The basis of this protein language is a kind of alphabet. It essentially consists of 20 building blocks analogous to letters. In proteins, however, it’s not about letters, but rather amino acids. Each protein is built up from a certain sequence of these amino acids; the sequence in turn largely determines its properties. Researchers would now like to know which protein sequence leads to which property. This is where so-called large language models such as GPT4 come into play. The AI chatbot ChatGPT, which has been causing a stir since 2022, is based on GPT4. Both were developed by the company OpenAI. ChatGPT uses an extensive dataset of texts created by humans to learn the patterns and structures of language. When the user enters a question or task, the model produces a response based on its understanding of the contexts and patterns that it learned during training. In this way it can write poems, novels and even programming code.

Flurin Hidber, a doctoral candidate supervised by Xavier Deupi, an expert in bioinformatics and protein structure at PSI, uses AI in protein research. Hidber uses a sophisticated model similar to ChatGPT that is trained to predict amino acids in protein sequences, instead of generating human-like language. This unique ability does not merely mimic the predictive capabilities of language models in AI, but rather provides valuable insights into the structure and function of proteins. Pharmaceutical researchers could use these to tailor medications and significantly shorten the process of trial and error in the laboratory, which in the end yields only a small proportion of drug candidates with promising properties.

An ambitious goal

Deupi and Hidber are working towards an ambitious goal: being able to determine the precise amino acid sequence that leads to a desired protein property. One focus of their research is light-sensitive proteins, a speciality of Deupi’s group and a research subject at SwissFEL. These proteins occur in many organisms, from microbes to humans, and have medical potential. Hidber’s use of AI to predict the properties of light-sensitive proteins solely on the basis of the sequence of their building blocks represents a significant advance in this field.

Through the precise prediction of the light-absorption properties of proteins, Hidber’s work could pave the way for the development of molecules with tailored properties – a step that could have a profound impact on optogenetics. This scientific technique employs light to control and monitor the activity of certain cells in living organisms, such as nerve cells in the brain. Researchers insert genes for light-sensitive proteins into these cells so they can precisely influence the cells’ behaviour by irradiating them with light.

This technology could contribute to the understanding and treatment of neurological diseases, since it provides a tool that can be used to investigate and control the activity of specific brain cells with unprecedented precision. For the future, Deupi and Hidber have set themselves the goal of reversing this process. They want to design new proteins with properties tailored to meet specific requirements, for example proteins that react to light of a particular colour. This blueprint could then be checked experimentally, and hopefully confirmed by colleagues in the laboratory.

The topic of protein dynamics is also at the heart of Cecilia Casadei’s research. The physicist has developed a new algorithm that enables more efficient evaluation of measurements at X-ray free-electron laser facilities such as SwissFEL. The building blocks of life often perform ultrafast movements. Investigating these with precision is crucial to gain a better understanding of proteins. In the long run, this can provide valuable information about disease processes and enable the development of novel medical approaches.

Read more on PSI website

Image: Xavier Deupi (left) and Flurin Hidber from the research group for Condensed Matter Theory want to better understand how the function of proteins is related to their structure. They are targeting light-sensitive proteins in particular. 

Credit:  Paul Scherrer Institute/Markus Fischer; KI image generation: Studio HübnerBraun/Midjourney

 SLS 2.0 upgrade 

 SLS 2.0 upgrade 

“The philosophy of the SLS has always been to explore novel techniques and use cutting-edge hardware, which has resulted in breakthroughs in areas such as imaging, X-ray spectroscopies, macro-molecular crystallography and detector technologies,” write Phil Willmott and Hans Braun in an article about the SLS 2.0 upgrade in Synchrotron Radiation News this month.

This philosophy of innovation underpins the comprehensive upgrade of the storage ring and X-ray sources of the Swiss Light Source SLS, which is currently underway. 

Better behaved electrons mean brighter X-ray light

The storage ring is the part of the facility where electrons zip around close to the speed of light, generating X-ray light as they go round the bends. The main parameter used to describe the quality of the X-ray light produced is brilliance, which effectively indicates how bright, compact, and well collimated the light is. 

For a more mathematical definition, brilliance is defined as the photon flux divided by the emittance – a parameter that describes how collimated the electron beam is and its cross-section in the storage ring. To maximise brilliance, the electron emittance should be as low as possible. 

This is the principle of a diffraction limited storage ring (DLSR): reducing electron emittance to the point that it is as small or smaller than that of the X-ray photons. The emittance of the X-ray photons is governed by fundamental diffraction phenomena. The performance of the synchrotron is thus limited by diffraction and no longer by the properties of the electron beam. 

The primary way in which this is achieved for SLS 2.0 is with an innovative arrangement of magnets for bending and focusing the electrons. By using more, smaller magnets, these smooth out the curves of the electrons round the storage ring, while keeping them close together. 

The new SLS 2.0 storage ring will allow the electron emittance to drop by a factor of thirty-five. With innovative new undulators enabling additional so-called radiation damping, the drop in electron emittance should exceed a factor of forty.

Read more on PSI website

Image: Work to install the new storage ring is already underway at the SLS. (Image: Paul Scherrer Institute

Credit: Markus Fischer

Altermagnetism proves its place on the magnetic family tree

Altermagnetism proves its place on the magnetic family tree

There is now a new addition to the magnetic family: thanks to experiments at the Swiss Light Source SLS, researchers have proved the existence of altermagnetism. The experimental discovery of this new branch of magnetism is reported in Nature and signifies new fundamental physics, with major implications for spintronics.

Magnetism is a lot more than just things that stick to the fridge. This understanding came with the discovery of antiferromagnets nearly a century ago. Since then, the family of magnetic materials has been divided into two fundamental phases: the ferromagnetic branch known for several millennia and the antiferromagnetic branch. The experimental proof of a third branch of magnetism, termed altermagnetism, was made at the Swiss Light Source SLS, by an international collaboration led by the Czech Academy of Sciences together with Paul Scherrer Institute PSI.

The fundamental magnetic phases are defined by the specific spontaneous arrangements of magnetic moments – or electron spins – and of atoms that carry the moments in crystals. Ferromagnets are the type of magnets that stick to the fridge: here spins point in the same direction, giving macroscopic magnetism. In antiferromagnetic materials, spins point in alternating directions, with the result that the materials possess no macroscopic net magnetisation – and thus don’t stick to the fridge. Although other types of magnetism, such as diamagnetism and paramagnetism have been categorised, these describe specific responses to externally applied magnetic fields rather than spontaneous magnetic orderings in materials.

Altermagnets have a special combination of the arrangement of spins and crystal symmetries. The spins alternate, as in antiferromagnets, resulting in no net magnetisation. Yet, rather than simply cancelling out, the symmetries give an electronic band structure with strong spin polarization that flips in direction as you pass through the material’s energy bands – hence the name altermagnets. This results in highly useful properties more resemblant of ferromagnets, as well as some completely new properties.

A new and useful sibling

This third magnetic sibling offers distinct advantages for the developing field of next-generation magnetic memory technology, known as spintronics. Whereas electronics makes use only of the charge of the electrons, spintronics also exploits the spin-state of electrons to carry information.

Although spintronics has for some years promised to revolutionise IT, it’s still in its infancy. Typically, ferromagnets have been used for such devices, as they offer certain highly desirable strong spin-dependent physical phenomena. Yet the macroscopic net magnetisation that is useful in so many other applications poses practical limitations on the scalability of these devices as it causes crosstalk between bits – the information carrying elements in data storage.

More recently, antiferromagnets have been investigated for spintronics, as they benefit from having no net magnetisation and thus offer ultra-scalability and energy efficiency. However, the strong spin-dependent effects that are so useful in ferromagnets are lacking, again hindering their practical applicability.

Here enter altermagnets with the best of both: zero net magnetisation together with the coveted strong spin-dependent phenomena typically found in ferromagnets – merits that were regarded as principally incompatible.

“That’s the magic about altermagnets,” says Tomáš Jungwirth from the Institute of Physics of the Czech Academy of Sciences, principal investigator of the study. “Something that people believed was impossible until recent theoretical predictions is in fact possible.”

Read more on PSI website

Image: Juraj Krempasky, scientist at PSI and first author of the Nature publication. The experimental proof of altermagnetism was made at the SIS (COPHEE endstation) and ADRESS beamlines of the SLS.

Credit: Paul Scherrer Institut / Mahir Dzambegovic

Harnessing EUV Light for Large-Scale Silicon Quantum Device Patterning

Harnessing EUV Light for Large-Scale Silicon Quantum Device Patterning

Extreme-ultraviolet light (EUV) is the key to state-of-the-art mass production of the classical electronics which drives the continuing information revolution. Scientists from PSI, UCL, EPFL and ETHZ have now used the Swiss Light Source (SLS) to perform the first experiments to demonstrate the potential of EUV for the manufacture of silicon-based quantum nanoelectronics, the building block for truly scalable quantum computers.

In the rapidly advancing domain of semiconductor technologies and quantum computing, scientists have developed methods to engineer devices at the atomic scale. Yet, the challenge of patterning large-scale devices remains a significant obstacle to scale-up, particularly when it comes to fabricating extensive arrays required for dopant-based qubits in silicon. One traditional method relies on the scanning tunnelling microscope (STM), where the high current density of electrons tunnelling from a sharp tip are used to pattern hydrogen-passivated silicon with an atomic-scale precision. But what if we could accomplish this feat using photons instead?

Photons, which are integral to high-volume semiconductor manufacturing through extreme ultra-violet (EUV) lithography, enable the patterning of arrays of billions of transistors to then yield high performance microprocessor, GPU or memory chips, thanks to the use of reflective masks. Now, a team of researchers led by Dr Procopios Constantinou from the Paul Scherrer Institute (PSI) and Associate Professor Steven Schofield from University College London (UCL) have demonstrated for the first time that hydrogen atoms can be desorbed from hydrogen-passivated silicon surfaces using EUV light instead of an STM. This ground-breaking research, published in Nature Communications, provides a path to patterning dopant atoms into silicon over large areas, bridging the gap between atomic-scale STM patterning and large-scale industrial semiconductor manufacturing.

Read more on PSI website

Image: This image provides an artist’s interpretation of the experiment, complemented by actual data. The black and blue spheres symbolize hydrogen and silicon atoms, respectively. A beam of incident EUV light hits the sample, triggering the desorption of hydrogen atoms from the surface. This process enables the execution of hydrogen desorption lithography. The bottom two panels display data from Scanning Tunnelling Microscopy (STM). The left panel shows an STM of hydrogen-terminated silicon, revealing an atomically clean and smooth surface. Each ‘hole’ in the hydrogen mask appears as a bright protrusion, representing a dangling bond. The right panel presents an STM after EUV exposure. It reveals that the surface is now covered with dangling bonds due to the desorption of hydrogen.

Listening for Defects as They Happen

Listening for Defects as They Happen

Thanks to experiments at the Swiss Light Source SLS, a Swiss research team have resolved a long-standing debate surrounding laser additive manufacturing processes with a pioneering approach to defect detection.

The progression of laser additive manufacturing — which involves 3D printing of metallic objects using powders and lasers — has often been hindered by unexpected defects. Traditional monitoring methods, such as thermal imaging and machine learning algorithms, have shown significant limitations. They often either overlook defects or misinterpret them, making precision manufacturing elusive and barring the technique from essential industries like aeronautics and automotive manufacturing. But what if it were possible to detect defects in real time based on the differences in the sound the printer makes during a flawless print and one with irregularities? Up until now, the prospect of detecting these defects this way was deemed unreliable. However, a research team from EPFL, Paul Scherrer Institute PSI and the Swiss Federal Laboratories for Materials Science and Technology (Empa) have successfully challenged this assumption.

Roland Logé, head of the Laboratory of Thermomechanical Metallurgy at EPFL who led the study, stated, “There’s been an ongoing debate regarding the viability and effectiveness of acoustic monitoring for laser-based additive manufacturing. Our research not only confirms its relevance but also underscores its advantage over traditional methods.”

This research is of paramount importance to the industrial sector as it introduces a groundbreaking, yet cost-effective solution to monitor and improve the quality of products made through Laser Powder Bed Fusion (LPBF). Lead researcher, Milad Hamidi Nasab, remarked, “The synergy of synchrotron X-ray imaging with acoustic recording provides real-time insight into the LPBF process, facilitating the detection of defects that could jeopardize product integrity.” In an era where industries continuously strive for efficiency, precision, and waste reduction, these innovations not only result in significant cost savings but also boost the dependability and security of manufactured products.

LPBF is a cutting-edge method that’s reshaping metal manufacturing. Essentially, it uses a high-intensity laser to meticulously melt minuscule metal powders, creating layer upon layer to produce detailed 3D metallic constructs. Think of LPBF as the metallic version of a conventional 3D printer, but with an added degree of sophistication. Rather than melted plastic, it employs a fine layer of microscopic metal powder, which can vary in size from the thickness of a human hair to a fine grain of salt (15–100 μm). The laser moves across this layer, melting specific patterns based on a digital blueprint. This technique enables the crafting of bespoke, complex parts like lattice structures or distinct geometries, with minimal excess. Nevertheless, this promising method isn’t devoid of challenges.

When the laser interacts with the metal powder, creating what is known as a melt pool, it fluctuates between liquid, vapor, and solid phases. Occasionally, due to variables such as the laser’s angle or the presence of specific geometrical attributes of the powder or of the part, the process might falter. These instances, termed “inter-regime instabilities”, can sometimes prompt shifts between two melting methods, known as “conduction” and “keyhole” regimes. During unstable keyhole regimes, when the molten powder pool delves deeper than intended, it can create pockets of porosity, culminating in structural flaws in the end product. To facilitate the measurement of the width and depth of the melt pool in X-ray images, the Image Analysis Hub of the Center for Imaging developed an approach that makes it easier to visualize small changes associated with the liquid metal and a tool for annotating the melt pool geometry.

Read more on PSI website

Image: By studying 3D metal printing in action simultaneously with X-rays imaging at the TOMCAT beamline and acoustic measurements, the research team could learn which sounds corresponded to defects in printing.

Credit:EFPL / Titouan Veuillet

Smart glass and music from SLS

Smart glass and music from SLS

Every year the PSI Founder Fellowship Programme supports new ideas for innovative applications with up to 150,000 Swiss francs. Whether smart glass or music restoration at the synchrotron – the resulting spin-offs are as diverse as the research at PSI.

Glass is no modern invention – in fact, archaeological finds show that this material has been manufactured and used by humans for more than 5,000 years. Glass is not only used as a vessel for fine wines – optical lenses are also ground from glass to make the smallest or most distant objects visible. Our communications flow through glass fibres in optical cables. Windows keep out the wind and rain while letting light pass through. The translucent material finds application in numerous areas of our civilisation. Yet glass is not just glass – we adapt it to our needs and reinvent it more or less constantly.

Barbara Horvath works with glass. The materials scientist, a candidate for the PSI Founder Fellowship, has been working to establish her spin-off Inveel since August of this year. Using tiny nanowires, the young entrepreneur wants to print electrodes on glass, for example to change its optical and electrical properties.

Smart glass

“One possible application for our technology is socalled switchable glass – also called smart glass,” Horvath explains. “That is a special material that can turn opaque, transparent dark or coloured, automatically or at the touch of a button.” This capability is enabled by a thin nanostructured coating sandwiched between two panes of glass. When electrical charges are applied to this layer, it becomes optically active and can change its colour as a result. This not only puts privacy at your fingertips, but can also be used to regulate the temperature in buildings.

The invention itself is not new. Such glass is already in use for windows in modern office buildings and aircraft, for example. However, producing them is very complex and thus costly. “To be able to apply the weak electrical charges to the switchable glass, thin wires must be accommodated – so thin that they will not impair visibility,” Horvath explains.

During her work at PSI, Horvath and her group leader Helmut Schift developed a method for the production of such fine conductor tracks. “Our method makes it possible to produce wires with a diameter of around one hundred nanometres,” the scientist explains. It functions much like a printer: nanoparticles are applied as liquid droplets and fuse together to form linear structures. This allows large areas to be printed with extremely fine, parallel conductors. Using conductive materials such as silver and gold, a wide variety of surfaces can be furnished with invisible electronics quickly and inexpensively.

Switchable glass is just one possible application. The nanowires could also be used to change the direction of polarisation of incident light in the glass so that only certain wavelengths penetrate. This could be used, for example, for temperature control in greenhouses or for laser protection in eyeglasses. “In the laboratory, we have shown that the technology works in principle,” Horvath adds. “The Founder Fellowship has now made it possible for us to take the next step towards practical applications.”

Read more on PSI website

Image: Barbara Horvath wants to use thin nanowires to alter the optical and electrical properties of glass.

Credit: Paul Scherrer Institute/Markus Fischer

SLS 2.0: “Dark time” during the upgrade

SLS 2.0: “Dark time” during the upgrade

The Swiss Light Source SLS at PSI will shut down temporarily as part of a major upgrade project. It will come back online in 2025, ready to supply even more powerful synchrotron light than ever for innovative scientific experiments.

At 8 a.m. on the morning of Saturday 30 September, the Swiss Light Source SLS, one of PSI’s five large research facilities, will be shut down. It will remain out of operation for research purposes for over a year while the facility undergoes a comprehensive modernisation programme: the SLS 2.0 upgrade project.

The SLS is Switzerland’s only research facility using synchrotron light. It supplies highly concentrated X-ray light for scientific experiments in many fields, such as physics, materials science, chemistry, biology and medicine. Since it first came into service in 2001, some 22,500 experiments have been performed at the SLS. In addition, external researchers have visited the SLS to conduct scientific experiments around 53,000 times in these 22 years.

The purpose of the current upgrade is to make the high-calibre facility fit to address the scientific challenges of future decades. The upgrade will greatly increase the density of the X-ray light: the beam will be even brighter and collimated stronger. This will allow more samples to be examined at the SLS over the same amount of time or to get more scientific data over the same period. In many cases, performance will improve by up to a factor of 40. In addition, researchers will be able to visualise larger areas of a sample. In other experiments, the resolution of the images will be increased, so that in future it will be possible to investigate even smaller structures, for example in the nanoscale.

Research into systems for the energy transition

The upgrade will mainly affect the 288-metre-long electron storage ring. A new vacuum tube will be fitted, along with around one thousand new, complex magnets that will hold the electrons with high precision on a then improved circular path. As the electrons are accelerated to almost the speed of light they release a special type of X-ray light, or synchrotron radiation. This is used for scientific research at around twenty beam lines around the ring.

Several new beamlines will also be set up as part of the upgrade, including the future Debye beamline. Here, researchers will be able to study materials and systems, such as catalysers and batteries, that can contribute towards the energy transition, not only with extreme precision, but under realistic operating conditions.

Other experimental stations at SLS are ideal for investigating the electronic or magnetic properties of materials that could be useful for the next generation of electronic devices, or for making non-destructive 3D recordings with a resolution of just a few nanometres. Yet other beamlines are used to examine proteins, the building blocks of life, whose precise knowledge helps to develop new medical agents.

Read more on PSI website

Image: PSI’s most iconic building, the Swiss Light Source SLS, is perfectly round and houses an electron storage ring with a circumference of 288 metres. Within this large-scale facility, electrons are accelerated to almost the speed of light and supply intense, highly concentrated synchrotron light to around 20 experimental stations for research purposes.

Credit: Paul Scherrer Institute/Michel Jaussi Photography

Thank You SLS

Thank You SLS

Since 2001, the Swiss Light Source SLS has been a catalyst for ground-breaking discoveries in physics, materials science, biology, and chemistry. The extremely bright X-ray light provided by the SLS has enabled researchers to take giant leaps in their understanding of the world around us.

Countless scientists in Switzerland and worldwide have collaborated at this remarkable facility, pushing the boundaries of scientific knowledge and unlocking new possibilities. As we approach the temporary shutdown for the SLS 2.0 upgrade, our beamline scientists look back on 22 years of brilliant science and achievements made possible by the SLS.

Read more on the PSI website

Image: Aerial veiw of the Swiss Light Source

Credit: PSI