How morphing materials store information

Experiments at SLAC’s X-ray laser reveal in atomic detail how two distinct liquid phases in these materials enable fast switching between glassy and crystalline states that represent 0s and 1s in memory devices.

Instead of flash drives, the latest generation of smart phones uses materials that change physical states, or phases, to store and retrieve data faster, in less space and with more energy efficiency. When hit with a pulse of electricity or optical light, these materials switch between glassy and crystalline states that represent the 0s and 1s of the binary code used to store information.
Now scientists have discovered how those phase changes occur on an atomic level.
Researchers from European XFEL and the University of Duisburg-Essen in Germany, working in collaboration with researchers at the Department of Energy’s SLAC National Accelerator Laboratory, led X-ray laser experiments at SLAC that collected more than 10,000 snapshots of phase-change materials transforming from a glassy to a crystalline state in real time.

>Read more on the LCLS at SLAC website

Image: The research team after performing experiments at SLAC’s Linac Coherent Light Source X-ray laser.
Credit: Klaus Sokolowski-Tinten/University of Duisburg-Essen)

Please read also the article published on the EUXFEL website:
Rigid bonds enable new data storage technology

Electric dipoles form chiral skyrmions

Control of such phenomena could one day lead to low-power, nonvolatile data storage as well as to high-performance computers.

A group of researchers, led by scientists from Berkeley Lab’s Materials Sciences Division and UC Berkeley’s Materials Science and Engineering Department, set out to find ways to control how heat moves through materials. They fabricated a material with alternating layers of strontium titanate, which is an electrical insulator, and lead titanate, a ferroelectric material with a natural electrical polarization that can be reversed by the application of an external electric field.

When the group took the material to Berkeley Lab’s Molecular Foundry for atomic-resolution scanning transmission electron microscope (STEM) measurements, however, they found something completely unexpected: bubble-like formations had appeared throughout the material, even at room temperature.

>Read more on the ALS website

Image: (a) Hard x-ray studies showed the presence of two sets of ordering: regular peaks along the out-of-plane direction (Qz), related to superlattice periodicity (about 12 nm), and satellite peaks in the in-plane direction (Qy), corresponding to the in-plane skyrmion periodicity (about 8 nm). (b) RSXD studies were performed at the in-plane satellite peaks, which correspond to the periodic polarization texture of the skyrmions’ Bloch components. (c) Spectra from a satellite peak for right- (red) and left- (blue) circularly polarized light. (d) The same spectra with background fluorescence subtracted. (e) The difference spectrum shows a clear circular dichroism peak at the titanium L3 t2g edge.

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

Scientists design organic cathode for high performance batteries

The new, sulfur-based material is more energy-dense, cost-effective, and environmentally friendly than traditional cathodes in lithium batteries.

Researchers at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have designed a new, organic cathode material for lithium batteries. With sulfur at its core, the material is more energy-dense, cost-effective, and environmentally friendly than traditional cathode materials in lithium batteries. The research was published in Advanced Energy Materials on April 10, 2019.

Optimizing cathode materials

From smartphones to electric vehicles, the technologies that have become central to everyday life run on lithium batteries. And as the demand for these products continues to rise, scientists are investigating how to optimize cathode materials to improve the overall performance of lithium battery systems.
“Commercialized lithium-ion batteries are used in small electronic devices; however, to accommodate long driving ranges for electric vehicles, their energy density needs to be higher,” said Zulipiya Shadike, a research associate in Brookhaven’s Chemistry Division and the lead author of the research. “We are trying to develop new battery systems with a high energy density and stable performance.”

>Read more on the NSLS-II website

Image: Lead author Zulipiya Shadike (right) is pictured at NSLS-II’s XPD beamline with lead beamline scientist and co-author Sanjit Ghose (left).

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

New lens system for brighter, sharper diffraction images

Researchers from Brookhaven Lab designed, implemented, and applied a new and improved focusing system for electron diffraction measurements.

To design and improve energy storage materials, smart devices, and many more technologies, researchers need to understand their hidden structure and chemistry. Advanced research techniques, such as ultra-fast electron diffraction imaging can reveal that information. Now, a group of researchers from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have developed a new and improved version of electron diffraction at Brookhaven’s Accelerator Test Facility (ATF)—a DOE Office of Science User Facility that offers advanced and unique experimental instrumentation for studying particle acceleration to researchers from all around the world. The researchers published their findings in Scientific Reports, an open-access journal by Nature Research.
Advancing a research technique such as ultra-fast electron diffraction will help future generations of materials scientists to investigate materials and chemical reactions with new precision. Many interesting changes in materials happen extremely quickly and in small spaces, so improved research techniques are necessary to study them for future applications. This new and improved version of electron diffraction offers a stepping stone for improving various electron beam-related research techniques and existing instrumentation.

>Read more on the NSLS-II at Brookhaven Lab website

Image: Mikhail Fedurin, Timur Shaftan, Victor Smalyuk, Xi Yang, Junjie Li, Lewis Doom, Lihua Yu, and Yimei Zhu are the Brookhaven team of scientists that realized and demonstrated the new lens system for as ultra-fast electron diffraction imaging.

The best topological conductor yet: spiraling crystal is the key to exotic discovery

X-ray research at Berkeley Lab reveals samples are a new state of matter

The realization of so-called topological materials – which exhibit exotic, defect-resistant properties and are expected to have applications in electronics, optics, quantum computing, and other fields – has opened up a new realm in materials discovery.
Several of the hotly studied topological materials to date are known as topological insulators. Their surfaces are expected to conduct electricity with very little resistance, somewhat akin to superconductors but without the need for incredibly chilly temperatures, while their interiors – the so-called “bulk” of the material – do not conduct current.
Now, a team of researchers working at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) has discovered the strongest topological conductor yet, in the form of thin crystal samples that have a spiral-staircase structure. The team’s study of crystals, dubbed topological chiral crystals, is reported in the March 20 edition of the journal Nature.

>Read more on the ALS at Berkeley Lab website

Image: This illustration shows a repeated 2D patterning of a property related to electrical conductivity, known as the surface Fermi arc, in rhodium-silicon crystal samples.
Credit: Hasan Lab/Princeton University

Reversible lattice-oxygen reactions in batteries

The results open up new ways to explore how to pack more energy into batteries with electrodes made out of low-cost, common materials.

For a wide range of applications, from mobile phones to electric vehicles, the reversibility and cyclability of the chemical reactions occurring inside a rechargeable battery are key to commercial viability. Conventional wisdom had held that involving oxygen in a battery’s electrochemical operation spontaneously triggers irreversible oxygen losses and parasitic surface reactions, reducing reversibility and safety. Recently however, the idea emerged that reactions involving lattice oxygen (i.e., oxygen that’s part of the crystal-lattice structure vs oxygen on the surface) could be useful for improving battery capacity. Here, researchers report the first direct quantification of a strong, beneficial, and highly reversible chemical reaction involving lattice oxygen in electrodes made with low-cost elements.

>Read more on the Advanced Light Source

Image: Advanced spectroscopy at the ALS clearly resolves the activities of cations and anions (known in Chinese as “yin” and “yang” ions) in battery electrodes.

Signatures of enhanced superconducting phase coherence in cuprates

The capability to control material properties on short timescales is one of the key challenges of modern condensed matter physics. This possibility becomes even more attractive in the case of intriguing material phases, such as superconductivity. As a matter of fact, despite the evolution of non-equilibrium spectroscopies of the last two decades have increased our understanding of the physics of strongly correlated materials, after more than 30 years from its discovery, High Temperature Superconductivity is still discussed and a clear and unanimous explanation of the origin of the phenomenon is still lacking. Moreover, the understanding of the phenomena at the basis of this effects could affect several technological applications, from the need for fast digital circuits and for speeding up computer performances, to the detection of very low magnetic fields, with implication in geology (mineral exploration and earthquake prediction), medical sciences (neuron activity and magnetic resonance), oil prospecting and, of course, research.
We focused our research on cuprates, a class of materials known for displaying unconventional superconductivity at relatively temperatures, and on which various studies have shown the possibility of turning off (and, to some extent, on) superconductivity by ultrashort light pulses. In our work, we reveal that light pulses characterized by long wavelength (and a peculiar polarization) can induce, for a very short time interval (1-2 ps), a state displaying superconductivity even above the critical temperature, i.e. in conditions where superconductivity is not observed at equilibrium.

>Read more on the FERMI at Elettra Sincrotrone Trieste website

Figure: Difference between the transient reflectivity due to Cu-Cu and Cu-O polarized pump in time and temperature, induced by excitations with (a) 70 and (b) 170 meV pump photon energies. The dashed lines highlight the critical temperature Tc.

A new lens allows researchers to watch shock waves travel through silicon

Researchers used a unique approach to learn more about what happens to silicon under intense pressure.

Elasticity, the ability of an object to bounce back to its original shape, is a universal property in solid materials. But when pushed too far, materials change in unrecoverable ways: Rubber bands snap in half, metal frames bend or melt and phone screens shatter.

For instance, when silicon, an element abundant in the Earth’s crust, is subjected to extreme heat and pressure, an initial “elastic” shock wave travels through the material, leaving it unchanged, followed by an “inelastic” shock wave that irreversibly transforms the structure of the material.

>Read more on the LCLS website

Image: After blasting silicon with intense laser pulses at SLAC’s Linac Coherent Light Source, researchers saw an unexpected shock wave appear in the material before its structure was irreversibly changed.
Credit: Gregory Stewart/SLAC National Accelerator Laboratory

New technique for two-dimensional material analysis

Discovery allows scientists to look at how 2D materials move with ultrafast precision.

Using a never-before-seen technique, scientists have found a new way to use some of the world’s most powerful X-rays to uncover how atoms move in a single atomic sheet at ultrafast speeds.

The study, led by researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and in collaboration with other institutions, including the University of Washington and DOE’s SLAC National Accelerator Laboratory, developed a new technique called ultrafast surface X-ray scattering. This technique revealed the changing structure of an atomically thin two-dimensional crystal after it was excited with an optical laser pulse.
>Read more on the Advanced Photon Source at Argonne website
>Another article is also available on the Linac Coheren Light Source at SLAC website

Image: An experimental station at SLACs Linac Coherent Light Source X-ray free-electron laser, where scientists used a new tool they developed to watch atoms move within a single atomic sheet.
Credit: SLAC National Accelerator Laboratory

A deep dive into the imperfect world of 2D materials

Berkeley Lab-led team combines several nanoscale techniques to gain new insights on the effects of defects in a well-studied monolayer material

Nothing is perfect, or so the saying goes, and that’s not always a bad thing. In a study at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), scientists learned how nanoscale defects can enhance the properties of an ultrathin, so-called 2D material. They combined a toolbox of techniques to home in on natural, nanoscale defects formed in the manufacture of tiny flakes of a monolayer material known as tungsten disulfide (WS2) and measured their electronic effects in detail not possible before. “Usually we say that defects are bad for a material,” said Christoph Kastl, a postdoctoral researcher at Berkeley Lab’s Molecular Foundry and the lead author of the study, published in the journal ACS Nano. “Here they provide functionality.”

Tungsten disulfide is a well-studied 2D material that, like other 2D materials of its kind, exhibits special properties because of its atomic thinness. It is particularly well-known for its efficiency in absorbing and emitting light, and it is a semiconductor.

>Read more on the Advanced Light Source website

Image: This image shows an illustration of the atomic structure of a 2D material called tungsten disulfide. Tungsten atoms are shown in blue and sulfur atoms are shown in yellow. The background image, taken by an electron microscope at Berkeley Lab’s Molecular Foundry, shows groupings of flakes of the material (dark gray) grown by a process called chemical vapor deposition on a titanium dioxide layer (light gray).
Credit: Katherine Cochrane/Berkeley Lab

First ever images of fuel debris fallout particles from Fukushima

Unique synchrotron visualisation techniques offer new forensic insights into the provenance of radioactive material from the Fukushima nuclear accident to understand the sequence of events related to the accident.

In April 2017, a joint team comprising the University of Bristol, the Japan Atomic Energy Agency (JAEA) and Diamond, the UK’s national synchrotronlight source, undertook the first experiment of its kind to be performed at Diamond.  A small radioactive particle (450μm x 280μm x 250 μm) from the Fukushima Daiichi nuclear accident in 2011 underwent a comprehensive and independent analysis of its internal structure and 3D elemental distribution, to establish the source of the material and the potential environmental risks associated with it.  

>Read more on the Diamond Light Source website

Image: Fukushima Particles research group (L-R): Cristoph Rau (I13), Yukihiko Satou, (researcher from the Collaborative Laboratories for Advanced Decommissioning Science, Japan Atomic Energy Agency), with Tom Scott and Peter Martin (University of Bristol).

Scientists develop printable water sensor

X-ray investigation reveals functioning of highly versatile copper-based compound

A new, versatile plastic-composite sensor can detect tiny amounts of water. The 3d printable material, developed by a Spanish-Israeli team of scientists, is cheap, flexible and non-toxic and changes its colour from purple to blue in wet conditions. The researchers lead by Pilar Amo-Ochoa from the Autonomous University of Madrid (UAM) used DESY’s X-ray light source PETRA III to understand the structural changes within the material that are triggered by water and lead to the observed colour change. The development opens the door to the generation of a family of new 3D printable functional materials, as the scientists write in the journal Advanced Functional Materials (early online view).

>Read more on the PETRA III at DESY website

Image: When dried, for example in a water-free solvent, the sensor material turns purple.
Credit: UAM, Verónica García Vegas

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

New insight into a puzzling magnetic phenomenon

ImagUsing an X-ray laser, researchers watched atoms rotate on the surface of a material that was demagnetized in millionths of a billionth of a second.

More than 100 years ago, Albert Einstein and Wander Johannes de Haas discovered that when they used a magnetic field to flip the magnetic state of an iron bar dangling from a thread, the bar began to rotate.

Now experiments at the Department of Energy’s SLAC National Accelerator Laboratory have seen for the first time what happens when magnetic materials are demagnetized at ultrafast speeds of millionths of a billionth of a second: The atoms on the surface of the material move, much like the iron bar did. The work, done at SLAC’s Linac Coherent Light Source (LCLS) X-ray laser, was published in Nature earlier this month.

>Read more on the LCLS at SLAC website

Image: Researchers from ETH Zurich in Switzerland used LCLS to show a link between ultrafast demagnetization and an effect that Einstein helped discover 100 years ago.
Credit: Dawn Harmer/SLAC National Accelerator Laboratory