From Berkeley Lab: “Whirlpools on the Nanoscale Could Multiply Magnetic Memory”

Berkeley Lab

At the Advanced Light Source, Berkeley Lab scientists join an international team to control spin orientation in magnetic nanodisks

May 21, 2013
Paul Preuss 510-486-6249 paul_preuss@lbl.gov

‘We spent 15 percent of home energy on gadgets in 2009, and we’re buying more gadgets all the time,’ says Peter Fischer of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). Fischer lets you know right away that while it’s scientific curiosity that inspires his research at the Lab’s Advanced Light Source (ALS), he intends it to help solve pressing problems.

The electron spins in a magnetic vortex all point in parallel, either clockwise or counterclockwise. Spins in the crowded core of the vortex must point out of the plane, either up or down. The four orientations of circularity and polarity could form the cells of multibit magnetic storage and processing systems.

‘What we’re working on now could make these gadgets perform hundreds of times better and also be a hundred times more energy efficient,’ says Fischer, a staff scientist in the Materials Sciences Division. As a principal investigator at the Center for X-Ray Optics, he leads ALS beamline 6.1.2, where he specializes in studies of magnetism.

Fischer recently provided critical support to a team led by Vojtĕch Uhlíř of the Brno University of Technology in the Czech Republic and the Center for Magnetic Recording Research at the University of California, San Diego. Researchers from both institutions and from Berkeley Lab used the unique capabilities of beamline 6.1.2 to advance a new concept in magnetic memory.

‘Magnetic memory is at the heart of most electronic devices,’ says Fischer, ‘and from the scientist’s point of view, magnetism is about controlling electron spin.’

Magnetic memories store bits of information in discrete units whose electron spins all line up in parallel, pointing one way or the opposite to signify a one or a zero. What Fischer and his colleagues propose is multibit storage in which each unit has four states instead of two and can store twice the information.

See the full article here. This may effect a lot of what you do.

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From Berkeley Lab: “Surprising Control over Photoelectrons from a Topological Insulator”

Berkeley Lab

Berkeley Lab scientists discover how a photon beam can flip the spin polarization of electrons emitted from an exciting new material

“Plain-looking but inherently strange crystalline materials called 3D topological insulators (TIs) are all the rage in materials science. Even at room temperature, a single chunk of TI is a good insulator in the bulk, yet behaves like a metal on its surface.

The interior bulk of a topological insulator is indeed an insulator, but electrons (spheres) move swiftly on the surface as if through a metal. They are spin-polarized, however, with their momenta (directional ribbons) and spins (arrows) locked together. Berkeley Lab researchers have discovered that the spin polarization of photoelectrons (arrowed sphere at upper right) emitted when the material is struck with high-energy photons (blue-green waves from left) is completely determined by the polarization of this incident light. (Image Chris Jozwiak, Zina Deretsky, and Berkeley Lab Creative Services Office)

Researchers find TIs exciting partly because the electrons that flow swiftly across their surfaces are ‘spin polarized’: the electron’s spin is locked to its momentum, perpendicular to the direction of travel. These interesting electronic states promise many uses – some exotic, like observing never-before-seen fundamental particles, but many practical, including building more versatile and efficient high-tech gadgets, or, further into the future, platforms for quantum computing.

A team of researchers from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley has just widened the vista of possibilities with an unexpected discovery about TIs: when hit with a laser beam, the spin polarization of the electrons they emit (in a process called photoemission) can be completely controlled in three dimensions, simply by tuning the polarization of the incident light.

‘The first time I saw this it was a shock; it was such a large effect and was counter to what most researchers had assumed about photoemission from topological insulators, or any other material,’ says Chris Jozwiak of Berkeley Lab’s Advanced Light Source (ALS), who worked on the experiment. ‘Being able to control the interaction of polarized light and photoelectron spin opens a playground of possibilities.’”

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From Berkeley Lab: “Searching for the Solar System’s Chemical Recipe”

Berkeley Lab

Berkeley Lab’s Chemical Dynamics Beamline points to why isotope ratios in interplanetary dust and meteorites differ from Earth’s

February 20, 2013
Paul Preuss

“By studying the origins of different isotope ratios among the elements that make up today’s smorgasbord of planets, moons, comets, asteroids, and interplanetary ice and dust, Mark Thiemens and his colleagues hope to learn how our solar system evolved. Thiemens, Dean of the Division of Physical Sciences at the University of California, San Diego, has worked on this problem for over three decades.

The protosun evolved in a hot nebula of infalling gas and dust that formed an accretion disk (green) of surrounding matter. Visible and ultraviolet light poured from the sun, irradiating abundant clouds of carbon monoxide, hydrogen sulfide, and other chemicals. Temperatures near the sun were hot enough to melt silicates and other minerals, forming the chondrules found in early meteoroids (dashed black circles). Beyond the “snowline” (dashed white curves), water, methane, and other compounds condensed to ice. Numerous chemical reactions contributed to the isotopic ratios seen in relics of the early solar system today.

In recent years his team has found the Chemical Dynamics Beamline of the Advanced Light Source (ALS) at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) to be an invaluable tool for examining how photochemistry determines the basic ingredients in the solar system recipe.

‘Mark and his colleagues Subrata Chakraborty and Teresa Jackson wanted to know if photochemistry could explain some of the differences in isotope ratios between Earth and what’s found in meteorites and interplanetary dust particles,’ says Musahid (Musa) Ahmed of Berkeley Lab’s Chemical Sciences Division, a scientist at the Chemical Dynamics Beamline who works with the UC San Diego team. ‘They needed a source of ultraviolet light powerful enough to dissociate gas molecules like carbon monoxide, hydrogen sulfide, and nitrogen. That’s us: our beamline basically provides information about gas-phase photodynamics.’”

At this point, I direct you to the full article. There is a lot going on here.

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From Berkeley Lab: “Nanocrystals Not Small Enough to Avoid Defects”

Berkeley Lab

Berkeley Lab Scientists at Advanced Light Source Show Dislocations Can Be Induced by Pressure in Ultrafine Nanocrystals

Interior of the ALS at Berkeley Lab

December 13, 2012
Lynn Yarris

“Nanocrystals as protective coatings for advanced gas turbine and jet engines are receiving a lot of attention for their many advantageous mechanical properties, including their resistance to stress. However, contrary to computer simulations, the tiny size of nanocrystals apparently does not safeguard them from defects.

Stress-induced deformation of nanocrystalline nickel reflects the dislocation activity observed by researchers at Berkeley Lab’s Advanced Light Source using a radial diamond-anvil-cell X-ray diffraction experimental station. (Image courtesy of NDT Education Resource Center)

A radial diamond-anvil-cell allows for in situ X-ray diffraction experiments at superbend beamline 12.2.2 of Berkeley Lab’s Advanced Light Source. (Photo by Roy Kaltschmidt)

In a study by researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab)and collaborators from multiple institutions, nanocrystals of nickel subjected to high pressure continued to suffer dislocation-mediated plastic deformation even when the crystals were only three nanometers in size. These experimental findings, which were carried out at Berkeley Lab’s Advanced Light Source (ALS), a premier source of X-rays and ultraviolet light for scientific research, show that dislocations can form in the finest of nanocrystals when stress is applied.

‘We cannot ignore or underestimate the role of dislocations – defects or irregularities – in fine nanocrystals as external stress can change the entire picture,’ says Bin Chen, a materials scientist with the ALS Experimental Systems Group who led this research. ‘Our results demonstrate that dislocation-mediated deformation persists to smaller crystal sizes than anticipated, primarily because computer models have not given enough consideration to the effects of external stress and grain boundaries.’”

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From Berkeley Lab: “Space-Age Ceramics Get Their Toughest Test”

Berkeley Lab

Berkeley Lab Researchers Develop Real-Time CT-Scan Test Rig For Ceramic Composites at Ultrahigh Temperatures

December 10, 2012
Lynn Yarris

“Advanced ceramic composites can withstand the ultrahigh operational temperatures projected for hypersonic jet and next generation gas turbine engines, but real-time analysis of the mechanical properties of these space-age materials at ultrahigh temperatures has been a challenge – until now. Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have developed the first testing facility that enables CT-scanning of ceramic composites under controlled loads at ultrahigh temperatures and in real-time.

These CT scans showing the formation of microcracks in ceramic composites under applied tensile loads at 1,750 degrees Celsius were obtained at Berkeley Lab’s Advanced Light Source through the use of a unique mechanical testing rig. (No image credit)

Working at Berkeley Lab’s Advanced Light Source (ALS), a premier source of X-ray and ultraviolet light beams, the scientists created a mechanical testing rig for performing X-ray computed microtomography that reveals the growth of microcrack damage under loads at temperatures up to 1,750 degrees Celsius. This allows engineers to compute a ceramic composite material’s risk of structural or mechanical failure under extreme operating conditions, which in turn should enable the material’s performance and safety to be improved.

‘The combination of our in situ ultrahigh temperature tensile test rig and the X-rays at ALS Beamline 8.3.2 allows us to obtain measurements of the mechanical properties of advanced ceramic materials at temperatures that are literally unprecedented,’ says Berkeley Lab materials scientist Robert Ritchie, who led this work. ‘These measurements, coupled with wonderful 3D images and quantitative data of the damage under load, can provide crucial information to permit accurate predictions of a ceramic composite’s structural integrity and safe lifetime.’ “

Robert Ritchie (left) and Hrishikesh Bale at ALS Beamline 8.3.2 with the mechanical testing rig they developed for in situ ultrahigh temperature X-ray computed microtomography. (Photo by Roy Kaltschmidt)

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From SLAC: “Diamond-like Coating Improves Electron Microscope Images”

November 26, 2012
Mike Ross

“Coating the surface of a material with a single layer of diamond-like crystals greatly improves images of it taken with an electron microscope, according to a study led by scientists at SLAC National Accelerator Laboratory and Stanford University.

Adding a single layer of diamondoid crystals to a material’s surface greatly improves the resolution of photoelectron emission microscope images of its magnetic structure.

The tests were conducted at Lawrence Berkeley National Laboratory’s Advanced Light Source. Adding a single layer of diamondoid crystals to the surface of a cobalt-platinum magnetic alloy improved the resolution of the microscope image – the size of the smallest perceivable detail – from 25 nanometers, or billionths of a meter, to 10 nanometers. The diamondoids capture electrons emitted from the sample and re-emit them within a very narrow energy range, which can then be focused precisely.

In results published last month in Applied Physics Letters, the group reported a nearly three-fold improvement in the quality of photoelectron emission microscope (PEEM) images when they used the coating. PEEM images reveal important aspects of the sample’s surface structure, chemical bonding and magnetic properties.”

See the full article here.

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

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From Berkeley Lab Advanced Light Source: “Borrowing from Nature to Produce Highly Structured Biomimetic Materials”

Berkeley Lab

Advanced Light Source

Wednesday, 27 June 2012

“Natural biological tissues are often hierarchically structured, and these structures appear to correlate strongly with tissue properties and functionalities. Finding out how a tissue self-assembles from cellular proteins has captured the interest of many biologists and material scientists who are interested in borrowing from nature’s bag of tricks to synthesize artificial materials with desired properties. A team of Berkeley Lab and University of California, Berkeley, scientists has recently discovered a method for controlling the assembly of such complex structures covering a large area from identical helical building blocks, in this case a rod-shaped virus, an accomplishment that could accelerate the development of diverse functional materials.

Illustration revealing how the arrangement of molecular building blocks yields novel functional materials with unique properties, both in nature and in the laboratory. Courtesy of Z. Deretsky, National Science Foundation.

Schematic diagram of the phage-based self-templating process. Left: The phage structure covered by about 2,700 alpha-helical major coat protein subunits having five-fold helical symmetry and a two-fold screw rotation axis (red and green arrows). Right: The self-templating assembly of phage particles. The morphology is controlled by competing interfacial forces at the meniscus where liquid-crystal phase transitions occur. The polarized optical microscopy image shows iridescent colors originating from liquid-crystal phase formation at the air–liquid–solid interface.

A self-templated helical supramolecular structure. Top center: AFM image of a left-handed smectic helicoidal nanofilament structure, which is composed of 1-µm bundles (left), and proposed model (right) of the nanofilament. The full structure consists of both left- and right-handed filaments. Bottom center: Grazing-incidence small-angle x-ray scattering measurement perpendicular to the pulling direction in a film with pseudo-hexagonally packed phage structures.

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From Berkeley Lab: “Molecular Spectroscopy Tracks Living Mammalian Cells in Real Time as They Differentiate”

Berkeley Lab

Berkeley Lab scientists demonstrate the promise of synchrotron infrared spectroscopy of living cells for medical applications

April 30, 2012
Paul Preuss

“Knowing how a living cell works means knowing how the chemistry inside the cell changes as the functions of the cell change. Protein phosphorylation, for example, controls everything from cell proliferation to differentiation to metabolism to signaling, and even programmed cell death (apoptosis), in cells from bacteria to humans. It’s a chemical process that has long been intensively studied, not least in hopes of treating or eliminating a wide range of diseases. But until now the close-up view – watching phosphorylation work at the molecular level as individual cells change over time – has been impossible without damaging the cells or interfering with the very processes that are being examined.

‘To look into phosphorylation, researchers have labeled specific phosphorylated proteins with antibodies that carry fluorescent dyes,’ says Hoi-Ying Holman of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). That gives you a great image, but you have to know exactly what to label before you can even begin.’

‘Now we can follow cellular chemical changes without preconceived notions of what they might be,’ says Holman, a pioneer in infrared (IR) studies of living cells who is director of the Berkeley Synchrotron Infrared Structural Biology program at Berkeley Lab’s Advanced Light Source (ALS) and head of the Chemical Ecology Research group in the Earth Sciences Division . ‘We’ve monitored unlabeled living cells by studying the nonperturbing absorption of a wide spectrum of bright synchrotron infrared radiation from the ALS.’ “

Berkeley Lab scientists observed phosphorylation in living PC12 cells stimulated by nerve growth factor as they differentiated and sent out neuron-like neurites. The researchers imaged individual cells and simultaneously obtained absorption spectra using synchrotron radiation from the Advanced Light Source. Cells not stimulated with nerve growth factor did not differentiate and showed different infrared absorption spectra. No image credit

There is a whole lot more to this article. See the full article here.

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From Berkeley Lab: “A Surprising New Kind of Proton Transfer”

Berkeley Lab

Paul Preuss
March 18, 2012

“When a proton – the bare nucleus of a hydrogen atom – transfers from one molecule to another, or moves within a molecule, the result is a hydrogen bond, in which the proton and another atom like nitrogen or oxygen share electrons. Conventional wisdom has it that proton transfers can only happen using hydrogen bonds as conduits, proton wires of hydrogen-bonded networks that can connect and reconnect to alter molecular properties.

Hydrogen bonds are found everywhere in chemistry and biology and are critical in DNA and RNA, where they bond the base pairs that encode genes and map protein structures. Recently a team of researchers using the Advanced Light Source (ALS) at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) discovered to their surprise that in special cases protons can find ways to transfer even when hydrogen bonds are blocked. The team’s results appear in Nature Chemistry.”

Hydrogen bonds are ubiquitous but nowhere more important than in the structure of DNA and RNA, where they join the ‘stair-step’ base pairs across the double strand. It has long been thought that protons transfer in molecules only by means of such hydrogen bonds. No image credit

See the full article here.
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From SLAC Today: “LCLS Offers New Method for Examining Membrane Proteins”

March 14, 2012
Diane Rezendes Khirallah

“Many membrane proteins serve as gateways in and out of the cell. Because they act as “traffic control” for infectious agents and disease-fighting drugs, they are the targets of more than 60 percent of all drugs on the market. Yet of the estimated 30,000 membrane proteins in the human body, scientists understand the detailed structures of only 18.

Now experiments at SLAC’s Linac Coherent Light Source (LCLS) have shown a promising new way to collect data on these elusive proteins. Researchers embedded tiny protein crystals in an oily paste that mimics the supportive environment of the cell membrane, and then hit them with a powerful X-ray laser to determine the protein’s structure. They reported their results in the March issue of Nature Methods.

Scientists embedded tiny protein crystals in an oily solution that mimics the supportive environment of the cell membrane, and then squirted them through a micro-jet into the path of a powerful X-ray laser. By analyzing the diffraction patterns made by X-rays scattering off the crystals, they were able to determine the protein’s structure. A key challenge was adjusting the viscosity of the oily solution, called a “lipidic sponge phase,” so it wouldn’t clog the micro-jet’s nozzle, shown here. Image courtesy Richard Neutze

Members of the large international research team represented more than a dozen institutions, including the Linac Coherent Light Source and Photon Ultrafast Laser Science and Engineering Center at SLAC; Gothenburg and Uppsala universities in Sweden; Arizona State University; the Center for Free-Electron Laser Science at DESY in Hamburg, Germany; DESY; the University of Hamburg; the Max Planck institutes for nuclear physics, extraterrestrial physics, semiconductor laboratory (Halbleiterlabor) and medical research; and the Advanced Light Source at the DOE’s Berkeley Lab.

See the full article here.

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.