Three research facilities reveal magnetic crossover

Spins tick-tock like a grandfather clock and then stop. Thanks to complementary experiments at the Swiss Muon Source SµS, Swiss Spallation Neutron Source SINQ and the Swiss Light Source SLS, researchers led by the University of Geneva have discovered this coveted characteristic, known as magnetic crossover, hidden within the magnetic landscape of an exotic layered material. Magnetic crossover means tuneability and with it promise for spin-based electronics.

A two-dimensional layered material that is magnetic and a small band gap semiconductor? For the electronics of tomorrow, you could say that Chromium Sulfide Bromide (CrSBr) has it all. “Any new magnetic features that you can find in the material can be useful from a practical point of view”, says Zurab Guguchia, scientist in muon spin spectroscopy at PSI. Together with clues from two other of PSI’s large research facilities, this technique would reveal the highly sought-after trait of magnetic crossover in this exciting new material.

The researchers discovered that as CrSBr is cooled, magnetic fluctuations in the material – where the spins tick-tock back and forth like a grandfather clock –  slow down and then freeze. This process is known as magnetic crossover. Interestingly, this is a gradual ‘crossover’ from one state to another, rather than a sharp transition that occurs at one temperature. And it is this characteristic that makes it such an appealing characteristic for spin based electronics devices, as Guguchia explains:

“We believe that this dynamic magnetic behaviour comes from competing interactions and frustrations that exist between the layers in the material. This means, with an external parameter we could tune it: push it in either direction. You couldn’t do this if it was just in one boring state.”

Read more on the PSI website

Image: To discover the hidden order within CrSBr’s magnetic structure, researchers needed complementary evidence from three different facilities: the Swiss Muon Source, the Swiss Spallation Neutron Source and the Swiss Light Source. With these techniques, they could reveal that spin fluctuations dwindled and then froze at 40 degrees Kelvin

Credit: Paul Scherrer Institute / Mahir Dzambegovic

Great minds think alike!

Marion Flatken from BESSY II & Luisa Napolitano from Elettra give advice to those at the start of their careers

Our #LightSourceSelfies campaign features staff and users from 25 light sources across the world. We invited them all to answer a specific set of questions so we could share their insights and advice via this video campaign. Today’s montage features Marion Flatken from BESSY II, in Germany, and Luisa Napolitano from Elettra, in Italy. Both scientists offered the same advice to those starting out on their scientific journeys: “Be curious and stay curious”. Light source experiments can be very challenging and the tough days can lead to demotivation and self-doubts. In these times, it is good to seek out support from colleagues, all of whom will have experienced days like this. Even if you think you can’t succeed with your research goals, try because it is amazing what can be achieved through hard work, tenacity and collaboration.

Unexpected Transformations Reinforce Roman Concrete

Researchers used the Advanced Light Source (ALS) to study binding phases in Roman architectural concrete, revealing reactions and profound transformations that contribute to the material’s long-term cohesion and durability.

The findings add to our growing understanding of cementing processes in Roman concretes, informing resilient materials of the future.

Marie Jackson, a research associate professor at the University of Utah, has devoted much of her career to understanding the scientific mysteries underlying the exceptional durability of Roman concretes. The ALS has been essential to her and her colleagues’ studies, helping to reveal the chemical and microstructural evolution of the materials.

Concrete is made of rock aggregates and a binder. Modern concretes typically use Portland cement—made by burning a mixture of limestone and clay at high temperature—as binder. Roman concretes, in contrast, consist of coarse volcanic rock (or brick) aggregate bound with mortar made from hydrated lime and reactive tephra—the particles ejected from explosive volcanic eruptions.

In this study, Jackson, along with collaborators Admir Masic and Linda Seymour of the Massachusetts Institute of Technology and Nobumichi Tamura of the ALS, examined mortar samples from the Tomb of Caecilia Metella in Rome. The team hoped that the 2,050-year-old monument would provide insights into how Roman builders’ selections of reactive volcanic rock influenced the material characteristics of the very robust concrete.

Read more on the ALS website

Image: The Tomb of Caecilia Metella on the Via Appia Antica in Rome. The edifice is one of the most refined concrete and dimension stone structures of the latest Roman Republican era.

Credit: Emmanuel Brunner

Photon Factory Highlights 2020

The research highlights based on the Photon Factory (PF) users’ program during fiscal 2020 (April 2020 – March 2021), is now available on the web.

The sections covered include:

Materials Science

Chemical Science

Earth & Planetary Science

Life Science

Instrumentation & Techniques


Access these highlights via the Photon Factory website

Image: Highlights 2020 cover

Credit: Photon Factory, KEK

One year of ESRF-EBS

One year ago, the ESRF switched on its Extremely Brilliant Source (EBS), a revolutionary new high-energy, fourth-generation synchrotron light source, a €150m project over 2015-2022 funded by ESRF’s 22 partner countries.

An accelerator physics dream saw the light with the launch of the world’s brightest synchrotron source, ESRF-EBS, inspiring many constructions and upgrades of synchrotron light sources around the world. Thanks to its enhanced performances, EBS has opened new vistas for X-rays science, enabling scientists to bring X-ray science into research domains and applications that could not have been imagined a few years ago, and providing invaluable new insight into the microscopic and atomic structure of living matter and materials in all their complexity.

Today, the ESRF celebrates one year of user operation of EBS and one year of exciting new science. “Europe can be proud of this masterpiece of state-of-the-art technology and scientific vision,” says Helmut Dosch, Chair of the ESRF Council.

Read more on the ESRF website

Image: Exterior view of the ESRF-EBS in Grenoble, France

Credit: ESRF

Grain-scale deformation of a high entropy alloy

New research that exploited the unique strengths of the FAST beamline produced some of the first measurements of individual grain deformation in high entropy alloys. This data can help form accurate predictions of damage and failure processes in these emerging materials, critical for understanding their performance in real-world applications.

Grains and strains | A subset of the thousands of indexed grains are shown, along with their axial elastic strains (top) and maximum resolved sheer stress (bottom), at 4 positions indicated on the stress-strain curve. This microscopic detail is only available via high-energy x-ray techniques.

What is the discovery?

Conventional alloys are made primarily of one metal element, with a small substitution of other atoms to tune the properties (for example, 7.5% Cu and 92.5% Ag produces sterling silver). Recently, new types of high entropy alloys (HEAs) have been discovered, which are made by mixing many different metallic elements in nearly-equal proportions. HEAs can exhibit remarkably different properties from conventional alloys. In a new paper, a team lead by Jerard Gordon from the University of Michigan reports a high-energy x-ray study of the HEA made from mixing equal amounts of Co, Cr, Fe, Mn, and Ni. The team was able to use far-field high-energy diffraction microscopy (ff-HEDM) to understand the microscopic response of thousands of individual crystal grains in their sample when it is deformed under load. They were also able to compare the results with detailed crystal-plasticity models.

Read more on the CHESS website

Image: Grains and strains | A subset of the thousands of indexed grains are shown, along with their axial elastic strains (top) and maximum resolved sheer stress (bottom), at 4 positions indicated on the stress-strain curve. This microscopic detail is only available via high-energy x-ray techniques.

Scientists glimpse signs of a puzzling state of matter in a superconductor

Known as “pair-density waves,” it may be key to understanding how superconductivity can exist at relatively high temperatures.

Unconventional superconductors contain a number of exotic phases of matter that are thought to play a role, for better or worse, in their ability to conduct electricity with 100% efficiency at much higher temperatures than scientists had thought possible – although still far short of the temperatures that would allow their wide deployment in perfectly efficient power lines, maglev trains and so on.

Now scientists at the Department of Energy’s SLAC National Accelerator Laboratory have glimpsed the signature of one of those phases, known as pair-density waves or PDW, and confirmed that it’s intertwined with another phase known as charge density wave (CDW) stripes – wavelike patterns of higher and lower electron density in the material.

Observing and understanding PDW and its correlations with other phases may be essential for understanding how superconductivity emerges in these materials, allowing electrons to pair up and travel with no resistance, said Jun-Sik Lee, a SLAC staff scientist who led the research at the lab’s Stanford Synchrotron Radiation Lightsource (SSRL).

Read more on the SLAC website

Image: SLAC scientists used an improved X-ray technique to explore exotic states of matter in an unconventional superconductor that conducts electricity with 100% efficiency at relatively high temperatures. They glimpsed the signature of a state known as pair density waves (PDW), and confirmed that it intertwines with another phase known as charge density wave (CDW) stripes – wavelike patterns of higher and lower electron density in the material. CDWs, in turn, are created when spin density waves (SDWs) emerge and intertwine.

Credit: Jun-Sik Lee/SLAC National Accelerator Laboratory

AI Agent Helps Identify Material Properties Faster

High-throughput X-ray diffraction measurements generate huge amounts of data. The agent renders them usable more quickly.

Artificial intelligence (AI) can analyse large amounts of data, such as those generated when analysing the properties of potential new materials, faster than humans. However, such systems often tend to make definitive decisions even in the face of uncertainty; they overestimate themselves. An international research team has stopped AI from doing this: the researchers have refined an algorithm so that it works together with humans and supports decision-making processes. As a result, promising new materials can be identified more quickly.

A team headed by Dr. Phillip M. Maffettone (currently at National Synchrotron Light Source II in Upton, USA) and Professor Andrew Cooper from the Department of Chemistry and Materials Innovation Factory at the University of Liverpool joined forces with the Bochum-based group headed by Lars Banko and Professor Alfred Ludwig from the Chair of Materials Discovery and Interfaces and Yury Lysogorskiy from the Interdisciplinary Centre for Advanced Materials Simulation. The international team published their report in the journal Nature Computational Science from 19 April 2021.

Read more on the BNL website

Image: Daniel Olds (left) and Phillip M. Maffettone working at the beamline.

Credit: BNL

New insights into the photochemical activity of titanium dioxide

Not so many compounds are as important to industry and medicine today as titanium dioxide (TiO2). The electronic structure of transition metal oxides is an important factor determining the chemical and optical properties of materials. Specifically for metal-oxide structures, the crystal-field interaction determines the shape and occupancy of electronic orbitals. Consequently, the crystal-field splitting and resulting unoccupied state populations can be foreseen as modeling factors of the photochemical activity. The research on titanium dioxide inaugurated the presence of IFJ PAN scientists in research programs carried out at the SOLARIS synchrotron. The measurements, co-financed by the National Science Center, were carried out at the XAS beamline.

In many chemical reactions, TiO2 appears as a catalyst. As a pigment, it occurs in plastics, paints, and cosmetics, while in medical implants, it guarantees their high biocompatibility. A group of scientists from the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Krakow, led by Dr. Jakub Szlachetka, engaged in research on the oxidation processes of the outer layers of titanium samples and related changes in the electronic structure of this material. Scientists from the IFJ PAN conducted their latest measurements, co-financed by the National Science Center, at the XAS beamline. They analyzed how X-rays are absorbed by the surface layers of titanium samples previously produced at the Institute under carefully controlled conditions.

Read more on the SOLARIS website

Researchers capture how materials break apart following an extreme shock

Understanding how materials deform and catastrophically fail when impacted by a powerful shock is crucial in a wide range of fields, including astrophysics, materials science and aerospace engineering. But until recently, the role of voids, or tiny pores, in such a rapid process could not be determined, requiring measurements to be taken at millionths of a billionth of a second.

Now an international research team has used ultrabright X-rays to make the first observations of how these voids evolve and contribute to damage in copper following impact by an extreme shock. The team, including scientists from the University of Miami, the Department of Energy’s SLAC National Accelerator Laboratory and Argonne National Laboratory, Imperial College London and the universities of Oxford and York published their results in Science Advances.

“Whether these materials are in a satellite hit by a micrometeorite, a spacecraft entering the atmosphere at hypersonic speed or a jet engine exploding, they have to fully absorb all that energy without catastrophically failing,” says lead author James Coakley, an assistant professor of mechanical and aerospace engineering at the University of Miami. “We’re trying to understand what happens in a material during this type of extremely rapid failure. This  experiment is the first round of attempting to do that, by looking at how the material compresses and expands during deformation before it eventually breaks apart.”

Read more on the SLAC website

Image: To see how materials respond to intense stress, researchers shocked a copper sample with picosecond laser pulses and used X-ray laser pulses to track the copper’s deformation. They captured how the material’s atomic lattice first compressed and subsequently expanded,, creating pores, or voids, that grew, coalesced, and eventually fractured the material.

Credit: Greg Stewart/SLAC National Accelerator Laboratory

Investigating 3D-printed structures in real time

Scientists used ultrabright x-rays to watch the developing structure of a 3D-printed part evolve during the printing process.

A team of scientists working at the National Synchrotron Light Source II (NSLS-II) at the U.S. Department of Energy’s (DOE’s) Brookhaven National Laboratory has designed an apparatus that can take simultaneous temperature and x-ray scattering measurements of a 3D printing process in real time, and have used it to gather information that may improve finished 3D products made from a large variety of plastics. This study could broaden the scope of the printing process in the manufacturing industry and is also an important step forward for Brookhaven Lab and Stony Brook University’s collaborative advanced manufacturing program.

The researchers were studying a 3D printing method called fused filament fabrication, now better known as material extrusion. In material extrusion, filaments of a thermoplastic—a polymer that softens when heated and hardens when cooled—are melted and deposited in many thin layers to build a finished structure. This approach is often called “additive” manufacturing because the layers add up to produce the final product.

Read more on the NSLS-II website

Image: The photo shows the research team, (from front to back) Yu-Chung Lin, Miriam Rafailovich, Aniket Raut, Guillaume Freychet, Mikhail Zhernenkov, and Yuval Shmueli (not pictured), placing the 3D printer into the chamber of the Soft Matter Interfaces (SMI) beamline at Brookhaven Lab’s National Synchrotron Light Source II (NSLS-II).

Note: this photo was taken in March 2020, prior to current COVID-19 social distancing guidelines.

How new materials increase the efficiency of direct ethanol fuel cells

A group from Brazil and an HZB team have investigated a novel composite membrane for ethanol fuel cells. It consists of the polymer Nafion, in which nanoparticles of a titanium compound are embedded by the rarely explored melt extrusion process. At BESSY II they were able to observe in detail, how the nanoparticles in the Nafion matrix are distributed and how they contribute to increase proton conductivity.

Ethanol has five times higher volumetric energy density (6.7 kWh/L) than hydrogen (1.3 kWh/L) and can be used safely in fuel cells for power generation. In Brazil in particular there is great interest in better fuel cells for ethanol as all the country distributes low-cost ethanol produced in a renewable way from sugar cane. Theoretically, the efficiency of an ethanol fuel cell should be 96 percent, but in practice at the highest power density it is only 30 percent, due to a variety of reasons. So there is great room for improvements.

Nafion with nanoparticles

A team led by Dr. Bruno Matos from the Brazilian research institute IPEN is therefore investigating novel composite membranes for direct ethanol fuel cells. A promising solution is tailoring new polymer-based composite electrolyte materials to replace the state-of-the-art polymer electrolyte such as Nafion. Matos and his team use melt extrusion process to produce composite membranes based on Nafion with additional titanate nanoparticles, which have been functionalized with sulfonic acid groups.

Read more on BESSY II (at HZB) website

Image: The material consists of Nafion with embedded nanoparticles.

Credit: © B.Matos/IPEN