SCIENCE, DISCOVERY & MAGNETISM
Science on the
Researchers on border patrol find fertile territory MRI Worth its Salt
A machine so strong it tracks sodium in your brain
Testing the Waters
What dissolved matter reveals about our changing planet
An Evening with Einstein
Dream dates with science celebs
Brought to you by the National MagLab
WINTER 2017
Welcome to our new (free) magazine! Here’s how to subscribe … Welcome to the inaugural issue of fields, a new magazine about high magnetic field research across the globe. We hope it engages, enlightens and even entertains you. To continue to receive free print copies of this new magazine, sign up at fieldsmagazine.org.
FIELD TRIP
World’s Strongest Human MRI Pack a sack lunch and load up! We’re hitting the road to learn how this massive magnet tracks sodium moving through your brain.
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SLOW TRAIN TO SCIENCE
From Frustration to Discovery Hitch a ride on this information train for a step-by-step look at how one physicist uses magnets to better understand superconductors, spin liquids and why some materials get frustrated.
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on the cover
INTERPOLAR
What’s in the Water? Studying dissolved organic matter helps us better understand our diverse and changing planet.
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COVER STORY
Science on the Edge
fields is produced at The National High Magnetic Field Laboratory (National MagLab) with the support of scientists around the world. Our goal is to show both doers and lovers of science some of the very cool things researchers discover about our world using high-field magnets. Director of Public Affairs
Kristin Roberts Editor
Kristen Coyne creative Director
Caroline McNiel Webmaster
Nilubon Tabtimtong Copy Editor Across disciplines, exciting stuff happens along the boundaries between things. What makes those realms so rich for research, and how do magnets shed light on them?
Barry Ray
fields Advisory Board
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SPECTRUM ANALYSIS
Dream Date with History Cocktails with the founder of modern physics, a frolic with the father of microbiology and other ideas for quality time with bygone science celebs.
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Kendra Frederick, The University of Southwestern Medical Center Laura Greene, National MagLab Chris Hendrickson, National MagLab Nigel Hussey, Nijmegen High Field Laboratory Huub Weijers, National MagLab Online fields magazine fieldsmagazine.org National MagLab NationalMagLab.org Contact us fieldsmagazine@magnet.fsu.edu
LEFT FIELD
Make It Better ‌ with a Bitter! The heart of a resistive magnet, the Bitter disk is too beautiful and versatile to be confined to the laboratory.
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Director Gregory S. Boebinger Deputy Director
Eric Palm
Proud member of the University Research Magazine Association fieldsmagazine.org
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Field trip
World’s Strongest Human MRI by Kristin Roberts
Pack a sack lunch and load up! We’re hitting the road to learn how this massive magnet tracks sodium moving through your brain.
Magnetic resonance imaging harnesses the power of magnets and radio waves to see inside the human body. Found in hospitals and doctors offices worldwide — in 2013, there were an average 14 MRI machines per million people in the 35 developed countries that comprise the Organization for Economic Cooperation and Development — MRI machines generally have a field strength of about 1.5 teslas (that’s the same as a junkyard magnet). Today’s field trip takes us to The University of Illinois Chicago (UIC) Medical Center to see a whopping 9.4-tesla MRI. Unveiled in 2003, this remarkable research tool measures nearly 3 meters tall and weighs as much as a humpback whale. The tunnel-like center of the magnet (known as the bore) is big enough to fit a linebacker, but researchers are particularly interested in using the magnet to see inside the human brain. While commercial MRIs detect hydrogen (or water) in the body, researchers require ultra-powerful magnetic fields to see sodium ions, a metabolic marker of healthy cells and tissues. Lower concentration of sodium indicates higher cell density — or more healthy cell-to-cell interactions — while higher sodium concentration shows a loss of cells. Scientists recently imaged sodium using this massive MRI to measure changes in brain cell density as we age.
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“We’ve known for some time that the human brain shrinks with normal aging,” explains Dr. Keith Thulborn, director of MRI research at the UIC College of Medicine and lead researcher on this work. “But this research shows that the shrinkage is not due to a loss of brain cells. Measuring sodium concentration, we can see that the number of brain cells and the density of those cells stay constant regardless of age.”
And while that finding is already exciting, Thulborn believes it could have even bigger implications on human health in the future. “Measuring sodium concentration to see these cell density changes could be the key to early identification of neurodegenerative diseases like Alzheimer’s which may show effects on the cellular level decades before clinical symptoms.” An even more powerful 10.5-tesla instrument is located at the University of Minnesota (research on humans is expected to begin in 2017), and an 11.7-tesla effort is underway through a collaboration between France and Germany. The strongest MRI for small animals — 21.1 teslas — is located at the National MagLab’s headquarters in Tallahassee, Florida.
Read this story at fieldsmagazine.org for links to more content.
Tissue sodium concentration maps of a 24-year-old (top) and a 73-year-old (bottom) made in the 9.4-tesla MRI show differences in cerebrospinal fluid (white) but little variance in brain tissue (green) despite age.
photos by: Hoss Fatemi
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Slow Train to Science
From Frustration to Discovery BY KRISTEN COYNE We all get frustrated when we don’t get what we want. Like when you go home after work and all you want is to grab a beer and crash on the couch. But your kids want dinner, the dog needs a walk, and the wifi is on the fritz again. Relaxation is hours away: So frustrating! Well, that happens to materials, too. Hop on this Slow Train to Science, and we’ll show you that their pain could be our science gain. The engineer on this train is Duke University physics professor Sara Haravifard. Haravifard is interested in spin liquids (read on for details of these exotic materials) and high-temperature superconductors, materials that conduct electricity without resistance at relatively high temperatures. Although they are a very hot topic of research, most have been discovered by accident. Haravifard wants to design them purposefully … and has plotted a route to get there. This train for the brain offers a variety of paths, including detours for passengers wanting more background. Feel free to customize your journey. All aboard!
hop on here! 1. COOK A CRYSTAL Haravifard begins by designing and synthesizing a magnetic crystal – specifically, a type of material called a frustrated magnet.
What’s a crystal? It’s a solid material in which all atoms, molecules and ions are strictly ordered in a lattice with a regular pattern that repeats in all directions. What makes it magnetic? You need to include a magnetic ion, such as copper, so that different parts of the crystal interact magnetically. How can a magnet be frustrated? It can’t settle down into its lowest-energy state ... more on that ahead! How does she make it? Haravifard generally uses a floating zone optical furnace that can reach 3,000°C (5,432°F) and makes very pure crystals. (Because they “float” in the furnace, the crystals don’t touch anything and stay pretty pure.)
The cool thing about magnetic crystals. Thanks to their magnetic moments, magnetic ions in the crystal interact with each other via their atomic bonds.
2. SHAKE IT UP Then it’s time to shake things up. Haravifard can fiddle with several parameters to influence how the magnetic ions in her crystal interact with each other. You could think of these as arrows in her scientific quiver. The first is chemical doping.
A crystal is a 3-dimensional structure, but physicists can study what happens in its 2-dimensional layers, where the magnetic behavior occurs.
Magnetic ions spin – kind of like a top – in a specific orientation, either “up” or “down.” Physicists call this a “magnetic moment,” or just “spin.”
She makes them stupid? Not at all. She substitutes some magnetic ions in her crystal for a non-magnetic ion (such as magnesium) or for a different magnetic ion with another atomic size. why? It’s like swapping out a family member for a total stranger: The interactions throughout the crystal lattice layer will be affected, resulting in a very different behavior.
8. SCIENCE SUCCESS! The knowledge gained from each experiment helps Haravifard refine her recipes for materials with exotic magnetic and electronic states and phase transitions, which she can then use in her continued search for new high-temperature superconductors.
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Sara Haravifard
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What questions? 1. What causes exotic states such as spin liquids or superconductivity to emerge from disordered states? 2. Is the transition sudden or gradual? 3. At what magnetic field strength does the transition take place? 4. Is there a relationship between spin liquids and superconductivity? 5. Can we induce a phase transition between the two states in a controlled way, for possible use in quantum computers?
3. CHILL OUT The next parameter is temperature – and this is where things get frustrating! Haravifard cools the crystal down to super-cold temperatures – where interesting quantum behaviors begin to emerge!
Why cool it? To remove the thermal energy.
4. SPIN CYCLE At a certain low temperature, this particular crystal undergoes a quantum phase transition ... specifically, it turns into a spin liquid.
What’s a phase transition? When a material changes from one state, or phase, to another – such as from solid ice to liquid water. Phase transitions occur also at the quantum, sub-atomic level (superconductivity is one example).
What’s a spin liquid? It’s a quantum state of matter that can happen in some materials at very cold temperatures when the spins pair up in a specific way (physicists call this entanglement).
How does she cool it? Liquid helium helps her chill the crystal down to close to absolute zero ... –273°C (or –459°F).
Then what happens? Most materials happily relax into their lowest-energy “ground” state. This means those magnetic moments align in the way that requires the least amount of energy.
What does that look like? Generally, that’s either ferromagnetic... all lined up in the same direction... or...
It’s not, despite its name, a liquid. But it resembles a liquid in that it’s not ordered (whereas solid ice is ordered into neat crystals).
5. ENERGY CRISIS The spin liquid is awesome! But it still is not ordered. It’s still frustrated! The colder it gets, the more it wants to order – and the more frustrated it gets because it can’t seem to get rid of that last bit of energy!
... antiferromagnetic, arranged up and down, up and down.
Why can’t they order? They can’t order because of their geometry. In an antiferrromagnetic system, for example, the lattice might be arranged in triangular configurations that prevent the moments of the magnetic ions from pairing off perfectly into up/down pairs. So two of the three ions will pair off as an up/ down duo, but the leftover third ion doesn’t know what to do! Should it pair up with the first ion and spin down? Should it pair up with the second ion and spin up? Getting mixed signals, it ends up spinning like a weathervane on a blustery day, preventing the system from ordering.
7. MAGNET: ON Now for the pièce de résistance! Time for Haravifard to pull out the final arrow in her quiver: a high magnetic field! This does the trick! Finally, the frustrated, disordered crystal becomes ordered!
How does this happen? The magnetic field exerts a torque on the magnetic ions in the crystal, forcing the spins to align into an ordered state. Why does Haravifard get so excited about this? 1.Such experiments can reveal a lot about the physics underlying cool phenomena such as spin liquids, and prompt lots of questions. 2. The more we know, the closer we are to exploiting these transitions for potential use in quantum computers.
6. APPLY Pressure With the material pushed to the brink with frustration, Haravifard pulls out another arrow: high pressure. It’s another way to tinker with the crystal. But it remains disordered ... and frustrated!
How much pressure? Up to tens of gigapascals of pressure – several orders of magnitude more than atmospheric pressure.
How does she pressurize it? She puts it inside a specially designed pressure cell.
Need another analogy? Think of a kid confused by conflicting messages. In answer to a question, Dad says, “No,” Mom says, “Yes.” Which one is it? Frustration, tantrums and other mayhem ensue!
What does this do, exactly? The pressure will physically squeeze the crystal, changing distances and angles between ions in the lattice. That structural change, with any luck, will help bring about a behavioral change in the material.
What’s that look like? It might change from something like this ...
to this ...
3. It’s inherently awesome!
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Interpolar
What’s in the water? 2
Studying dissolved organic matter helps us better understand our diverse and changing planet.
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With its striking blues and greens, our planet, viewed from space, seems neatly divided into water (covering roughly three-quarters of the Earth) and land. But in both terrestrial and aquatic systems, you’ll find plenty of something that’s a little of both — dissolved organic matter, or DOM.
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Although it might not be obvious from a satellite’s-eye view, DOM, originating from decomposing plants and animals, is critically important in biology and the environment. Found in wetlands, ice sheets, rivers, oceans, groundwater and permafrost across the globe, it plays a role in transporting nutrients, sequestering carbon and protecting underwater ecosystems from ultraviolet radiation. But DOM is a challenge to study: It moves around a lot and is very complex. In fact, a single liter of seawater contains more than a million different organic molecules, according to Thorsten Dittmar, a professor of marine geochemistry at the University of Oldenburg in Germany who has studied DOM extensively. Fortunately, Dittmar and other researchers at places such as Woods Hole Oceanographic Institution, the National MagLab and elsewhere have a great tool for analyzing the composition and behavior of DOM: Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. With these magnetdriven tools, they study issues related to climate change, agricultural nutrients, mercury contamination and much more. This Interpolar map gives an overview of what those scientists are learning across the globe. Visit fieldsmagazine.org for an interactive version of this map, more examples of DOM research and links to publications about the research featured here. -KC
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Moss inhibits greenhouse gas release
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Better treatments for toxic water
Water samples from a thawing subarctic peatland in northern Sweden indicate that sphagnum moss helps inhibit rapid decomposition and methane release there. That effect may disappear, however, if rising temperatures turn moss bogs into more waterlogged marshes.
Extracting bitumen (a highly viscous form of petroleum) from Canada’s Athabasca oil sands deposits results in vast quantities of processed water. Currently, that toxic water is stored in tailings ponds, and researchers are looking for better solutions. Scientists compared three methods of treating the water, and found that two significantly lowered the water’s toxicity.
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How do organisms absorb metals? In order for their enzymes to carry out essential metabolic functions, marine organisms need copper and nickel. The rate at which they absorb these metals from DOM often depends on the composition of those molecules in the organism responsible for capturing the metals. To better understand this, scientists characterized several discrete copper and nickel compounds in DOM samples collected from the tropical Pacific.
A plant’s voyage from land to sea Studying samples taken from the Subtropical Convergence off the New Zealand coast (where warm subtropical water mixes with cold subantarctic water), scientists found that a significant fraction of organic matter from land is transported to the open ocean. This suggests that many of the compounds in the oceanic organic carbon pool originate from land-based plants.
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Coastal areas store DOM
Among the most productive marine ecosystems, coastal areas are hotspots of the global carbon cycle. Studies in Northern Europe’s Wadden Sea — the world’s largest intertidal flat area — have shown that certain kinds of terrestrial and marine DOM are stored in coastal sediments while others are consumed by microbes there.
Coral reefs subtract and add DOM
Sponges in the Florida Keys filter large quantities of water during their lifetime, turning over the water every seven days. The sponges remove some molecules from reef seawater and deposit others, the latter of which could influence the chemistry and biology of microbes on reefs.
From ice sheet to ocean The source of DOM in waters exiting the Greenland Ice Sheet varies over the course of a melt season. At the beginning, DOM comes primarily from bedrock waters, which have existed at the base of the ice sheet over the winter. As the surface of the ice sheet melts and water drains to the bedrock, the DOM is increasingly influenced by surface waters. The DOM affects downstream rivers, fjords and the surrounding ocean.
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Human waste in the water
Water leaching from septic systems influences the quality of nearby groundwater. This leachate contains high levels of nitrogen molecules originating from humans, which can affect the water quality of nearby coastal waters and rivers.
DOM’s Amazonian journey Scientists connected the carbon cycle of the lower Amazon River to the open ocean, a link crucial for understanding how humans and climate change affect the system. They studied where DOM decomposes, where it’s taken in by microbes and where light works to degrade it. Still, a large proportion of Amazon DOM resists degradation by either microbes or light. So the river plume appears to contribute to the long-term storage of degradation-resistant organic carbon in the deep ocean.
charcoal ends up 10 Where Every year, wildfires turn millions of hectares of vegetation into charcoal, which is transported to the sea by rivers and enters the carbon cycle. Analyzing water samples from the Congo, the Yangtze and eight other rivers worldwide, researchers demonstrated that soluble charcoal accounts for 10 percent of all dissolved organic carbon.
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Scienc on the Edge by Kristen Coyne
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ce Across disciplines, exciting stuff happens along the boundaries between things. What makes those realms so rich for research, and how do magnets shed light on them? Fringe physics. Borderline biology. Crossover chemistry. No matter the name one might concoct to describe it, the phenomenon is the same from one field to the next: At the dividing line between two things, there’s often no hard line at all. Rather, there’s a system, phenomenon or region rich in diversity or novel behavior — something entirely different from the two things that created it. In ecology, they call this the ecotone — the transition area between adjacent ecosystems (forest meets meadow, say, or dunes meet ocean). In addition to being home to species from neighboring areas, this zone typically gives rise to unique flora and fauna found nowhere else. It’s referred to as the edge effect in the field, but scientists from other disciplines know it well, too. When things overlap, you often get more than the sum of those parts. Or as one chemist put it, A plus B isn’t necessarily AB: It’s probably something a lot more interesting. In the stories below, we learn about chemists, physicists and biologists who are pushing the boundaries of knowledge by exploring the boundaries between things. Exploiting high magnetic fields, they study how proteins police the walls of cells; how to break down the barrier between oil and water in emulsions; why electrons behave bizarrely near the surface of some materials; and which adjoining ingredients yield a better lithium ion battery.
It’s no accident many researchers focus on these threshold regions, said Holly FalkKrzesinski, an expert on interdisciplinary and team research at the scientific publishing giant Elsevier. “It turns out that work that’s done at the interstices, or the interfaces, tends to be highly innovative, higher-impact research,” she said. Although research that probes interfaces is not necessarily interdisciplinary, it often is. Interdisciplinary research is, after all, a kind of intellectual interface that can be very well suited to discovering fringe phenomena. Interdisciplinary research is on the rise and yielding important results, noted Falk-Krzesinski. In the long term, the more interdisciplinary an article is, the more citations it gets compared to other articles, according to a 2013 article in Science. Funding agencies are pushing researchers toward interdisciplinary approaches for problems that traditional research has failed to solve. And although academic traditions and infrastructures can inhibit interdisciplinary work, universities have found an effective work-around in the growth of interdisciplinary centers and institutes. “Innovation is about taking what we already have or what we already know and combining it with something new,” Falk-Krzesinski said. “And the ‘new’ doesn’t have to be brand new knowledge; the ‘new’ can be new information, new insight from an existing field.” Read on to learn how four researchers using magnetic fields explore science on the edge. fieldsmagazine.org
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Bursting the Oil / Water Bubble
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When two strong personalities clash, they’re likened to oil and water. But the two fluids can indeed mix, with droplets of H20 distributed throughout the oil in an emulsion. For crude oil companies, that can spell trouble. Whether companies extract oil from deep underground or from the surface, water inevitably ends up in the mix. While some naturally separates out, some can remain trapped in the oil as emulsified droplets, causing costly problems when the oil is processed. Oil companies wanted to burst those pesky water bubbles and figure out what their walls were made of. “If you knew their chemistry, then you could target them like a drug targets a virus, to knock them out,” said Ryan Rodgers, an expert in petroleum science at the National High Magnetic Field Laboratory who directs the Future Fuels Institute (FFI) based there. “Then you could free the water, then free the oil.” But before you can determine what’s in that wall, you have to isolate it. Rodgers and his team at FFI and the MagLab’s Ion Cyclotron Resonance (ICR) Facility came up with an ingenious way to do just that. They faced a sizeable challenge: Crude oil is the most chemically complex substance on Earth — a single sample can contain millions of different kinds of molecules. Some of these molecules are hydrophilic — so they are drawn to any water that gets mixed in the oil. As a result, they fuse into walls around areas of water, forming water droplets. The scientists needed to somehow identify, capture and remove those hydrophilic molecules.
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Ryan Rodgers photo by: Stephen Bilenky
So they created a clever trap for them designed around a simple grain of sand. They applied layer after layer of water onto silica until they figured out the exact amount needed to attract the problem molecules. (After a lot of trial and error, they discovered that 26 layers generally did the trick.) When the water-encased silica was added to the oil, the hydrophilic molecules in the droplet walls headed straight for them. This isolated the molecules that cause an emulsion. The silica (encased first by its shell of water, then by a layer of water-loving crude oil molecules) was easily separated out. Scientists then simply peeled the target molecules right off and analyzed them. Using ICR instruments that rely on powerful magnets, the chemists were able to precisely identify the molecules that were acting as surfactants, molecules that lower the surface tension between petroleum and water and allow emulsion droplets to form. What they saw surprised them. “We’ve been able to show that the chemical diversity of these naturally occurring surfactants in petroleum
is as complex as petroleum itself,” Rodgers said. “It’s just spectacular. You’re looking at hundreds of thousands of naturally occurring surfactants.” ICR and other analytical tools are now helping scientists learn more about those surfactants. Does that emulsion wall vary under different conditions, such as pH, for example? “The goal is to manipulate the chemistry of those walls so we can use it when it’s needed and get rid of it when we don’t,” Rodgers said. What scientists learn will also have applications in renewable fuels, whether extracted from algae, pine pellets, sugarcane or other biomass. “All of those materials have an enormous water content,” said Rodgers — water that needs to be removed before you can make fuel from it.
“A plus B doesn’t always equal AB. A plus B can sometimes be equal to Z.” Scientists studying fuels are interested in other problematic interfaces, too, such as fine particles like rust in crude oil. When two things abut, it’s never straightforward, requiring scientists to sort it all out. “It’s an issue because A plus B doesn’t always equal AB,” Rodgers said. “A plus B can sometimes be equal to Z.”
Surprise Under the Surface
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In her forays into physics, University of Cambridge physicist Suchitra Sebastian heads for the hinterlands, hoping to be the first to leave footprints. “I like to explore unknown territory,” she said. Which is not to say she’s wandering blindly into the science haystack. She has a definite strategy about where the coolest physics needles are hiding. Sebastian studies correlated electron systems — materials in which electrons can team up and behave radically differently from individual electrons. Recently, Sebastian has set her sites on samarium hexaboride (SmB6). Some physicists
Suchitra Sebastian photo by: Philipp Ammon / Quanta Magazine
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“My first reaction was, ‘Wow, something strange is happening.’” who have studied that system have proposed that it belongs to a class of materials called topological insulators. Discovered in 2007, topological insulators are the split personalities of materials: They conduct electricity in some areas, but don’t in others. In topological insulators that are two-dimensional (only one atomic layer thick), current runs only along the edges, like a racecar circling a track while avoiding the infield, which acts as an insulator. In 3-D topological insulators, current can run anywhere on the surface, but not through the interior (called the “bulk” by physicists). Picture that racecar speeding along any road on Earth, but never penetrating the planet. (If the term “topological” rings a bell, it might be because the 2016 Nobel Prize in Physics went to a trio of scientists who applied concepts of topology, a branch of mathematics, to better explain and predict so-called “exotic” states and transitions of matter.) Sebastian set out to try and establish the topological character of SmB6 by looking at how electrons travel through its conducting surface. As electrons propagate through a conductor, their orbits forge a rather zigzagging path. Because SmB6 was a supposed topological insulator, Sebastian expected that those orbits would be restricted to the very surface of the material — that their path would be strictly two-dimensional. But what Sebastian and her group found during experiments in 2015 was far stranger. When they studied SmB6 using a very high magnetic field, they found what appeared to be large, three-dimensional electron orbits. That would mean that the electron orbits were moving through the interior of the material, which is an insulator.
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“My first reaction was, ‘Wow, something strange is happening,’” said Sebastian, who was conducting the experiment at the National MagLab at the time. “How could we be seeing large electron orbits in the bulk? The electrons in the bulk of SmB6 shouldn’t be moving at all — the bulk is insulating!” She phoned a colleague at Cambridge for his thoughts. “You do realize,” he insisted, “this is impossible.” Apparently not. Sebastian has since been trying to figure out this unusual effect — a material that appears to behave simultaneously as an insulator and a conductor. Is it a never-before-observed quantum phase of matter? Could it be that electrons behaving collectively (known as quasiparticles) in this strange quantum phase act completely unlike individual electrons? “Perhaps the quasiparticles we see orbiting are starkly different from electrons or electron-like objects,” Sebastian suggested. “We begin to consider the radical possibility that perhaps SmB6 defies conventional understanding, and comprise neutral quasiparticles — ones that, unlike electrons, carry no charge!” In her search for answers, Sebastian sticks to the fringe. She focuses on critical phase transition regions — the thresholds between states of matter that occur at specific pressures or temperatures, like water boiling as it turns into steam under a critical pressure. “We are interested in the quantum version of this critical regime, where a growth of quantum fluctuations means that the interactions between electrons grow extremely large, mediating new and exotic quantum phases,” she said. “This region is therefore an incredibly exciting region that is ripe for exploration.”
Border Patrol
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“No man is an island,” English poet John Donne wrote almost 500 years ago. Neither, to put a modern, scientific twist on that famous line, are the things man is made of: cells. Cells are surrounded by a protective wall called the lipid bilayer. But they still, at that interface, need to interact with the outside world. That’s the job of membrane proteins, the bouncers of the cellular world. They police what comes in and what leaves while keeping an eye out for trouble. “They’re key players in allowing cells to adapt to new living conditions or to protect the cell from certain events happening outside,” explained Guido Pintacuda, research director at the Center for High Field Nuclear Magnetic Resonance (NMR) in Lyon, France. “For example, they are able to communicate to the outside world a change which is happening inside the cell. This immediately makes them important drug targets.” In fact, about 40 percent of all FDA-approved drugs are designed to manipulate membrane proteins in some way. Yet they remain largely a mystery. Despite their numbers (they make up about 20 to 30 percent of all living proteins) and the pivotal roles they play in our bodies, less than 2 percent of all the proteins scientists have characterized to date are membrane proteins. That’s because those boundary-dwellers are often in charge of complex tasks and need a complex structure to execute them. Typically they contain several hundred amino acids arranged in rigid scaffolds alternating with less-ordered portions.
Guido Pintacuda photo by: Loren Andreas and Michael J. Knight
Scientists also face big technical hurdles with the NMR instruments they use to understand what these proteins look like and how they function. But groups such as Pintacuda’s are developing new tricks to make solid-state NMR a more powerful and versatile tool for the job. “Increasingly it’s the technique of choice,” he said. Using solid-state NMR, scientists can map out the structure of complex macromolecules by using magnetic fields and radio waves that exploit magnetic properties inherent to all atoms. Depending on the specific technique applied, the result is either a “snapshot” detailing the molecule’s structure or a kind of movie that reveals how it behaves in its native environment. “We can see what happens to each atom of a large molecule over time,” Pintacuda said. “We can look at the molecule in three dimensions as it if was at the cinema, and we see how it functions.”
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“We can look at the molecule in three dimensions, as if it was at the cinema.” One protein much scrutinized by scientists working at the Francis Bitter Magnet Lab at MIT, the National MagLab and other labs is known as the M2 proton channel. Located in the wall of the influenza A virus, it ushers protons in and out of the cell. Tim Cross at the National MagLab discovered how the protein functions, and his and other groups are identifying new drugs to block it, thus preventing or thwarting infection. At the Center for High Field NMR in Lyon, Pintacuda’s group has helped its collaborators in
studying a mutated form of that protein on a drugresistant version of influenza A, shedding light on how the mutation allows the M2 proton channel to keep working even after exposure to drugs. Their NMR research would not be possible without high magnetic fields. The stronger their magnets, the better NMR systems can “hear” and separate the tiny signals emitted by different atoms in the molecules they’re listening to. One might imagine NMR like an elephant, an animal renowned for excellent hearing, thanks to its big, amplifier-like ears. Dr. Seuss fans might even bring to mind the author’s famous pachyderm, Horton, whose sensitive ears could make out voices of the residents of Whoville, who inhabited a speck of dust. “We’re able to isolate the voice of each individual atom in the molecule,” said Pintacuda, “and therefore much better characterize what’s happening at atomic resolution.”
Safer Lithium Batteries
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Yan-Yan Hu, a chemist at the National MagLab and Florida State University, loves composite materials. Thanks to all their interfaces, they are often more useful, and definitely more complex, than the sum of their parts. “When you add one element to the other,” said Hu, “that makes the whole system more complicated to study.” Bone is one such system, owing its amazing properties to its composite nature: strength from mineral, and flexibility from protein fibrils that offset the mineral’s brittleness.
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Yan-Yan Hu photo by: Stephen Bilenky
“So it’s a combination of both that produces these synergistic effects, that provides the biological function and the mechanical function,” Hu said. Hu earned her Ph.D. by solving one of the big bone mysteries. Using nuclear magnetic resonance (NMR), she discovered that citrate molecules at the interface of those two ingredients direct the formation of the composite bone matrix. Since then, Hu has gone from bones to batteries. In particular, she studies the interfaces between electrodes and the electrolyte of lithium ion batteries. Lithium has a lot going for it as a battery ingredient: It’s the lightest metal and has great electrochemical potential and energy density. But it has problems, too, including a spotty safety record. Like all batteries, lithium ion batteries have an anode and a cathode; lithium ions travel through the electrolyte between these two electrodes to generate energy. But even with just three main ingredients, problems pop up when you put them together. Materials accumulate on the electrodes’ surface, for example, lowering the battery’s capacity. And if the accretions of those metallic dendritic structures eventually reach the opposite electrode, they create a bridge that shorts the battery and causes it to overheat. Although most lithium batteries today use liquid electrolytes, scientists such as Hu are looking for a solid that could be safer (blocking the formation of those electronically conductive bridges) and yield more capacity. So they ask: What solid electrolytes will hold up at the interface with the electrodes? How do charges travel from one side to the other? Hu and her group experimented with a composite electrolyte — lanthanum lithium zirconium oxidepolyethylene oxide (LLZO-PEO) — that leverages useful properties of both ceramics and polymers. They wanted to know exactly how lithium ions would travel through LLZO-PEO: Through the ceramic? Through the polymer? Through the interface?
“There’s no way you can separate them and look at the interface. If you pull them apart, it’s not an interface anymore.” “It’s difficult to study the interface because it’s buried,” Hu explained. “The ceramic and the polymer are mixed together. There’s no way you can separate them and look at the interface. If you pull them apart, it’s not an interface anymore.” High-field NMR allowed Hu and her team a way to see those ions in action at the atomic level. They built small lithium-ion button cells and, with special equipment, observed where the lithium ions traveled while the cells charged and discharged inside a magnetic field. To do this, her team devised a trick: Use one isotope (or variation) of lithium in the electrolyte (in this case, lithium-7), and another isotope (lithium-6) in the electrodes. This allowed Hu to identify the ions’ pathway: The lithium-7 ions swapped out for lithium-6 ions wherever they traveled. That path, as it turned out, went through the ceramic. Knowledge like this can help engineers manipulate interfaces to design safer, more powerful battery materials.
Read this story at fieldsmagazine.org for links to more content.
It was a straightforward question — with a wellhidden answer.
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Spectrum Analysis
Dream Date with History From cocktails with the founder of modern physics to a frolic with the father of microbiology, researchers imagine quality time with science celebs of the past.
High magnetic field science attracts researchers from different disciplines and locations and with diverse opinions and experiences. We asked scientists from across this broad community, along with some science fans, to answer a simple, fun question in 140 characters: Who would you most like to meet from science history and what activity would you do together? Here are some of our favorite answers. Add your voice to the spectrum by tweeting us your answer @NationalMagLab or using #SpectrumAnalysis. - KR
To meet an intellect of profound influence whose work is lost to us, I’d take a trireme ride from Athens to Syracuse with Eudoxus of Cnidus.
I’d like to meet Kamerlingh Onnes and show him how much helium we use today. Jun Sum Kim, Pohang University of Science and Technology
Paul Cadden-Zimansky, Assistant Professor of Physics, Bard College
Illustration by Jodi Slade
I would love to have a dance with Antonie van Leeuwenhoek and then count bacteria with him using the microscope in my lab. Huan Chen, Visiting Research Faculty, National MagLab
I’d like to hang out with Ben Franklin and help him as he pioneered American meteorology in colonial times. Mike McCall, meteorologist, @WCTVMike
I’d like to meet Bernd T. Matthias and see how he set up his experiments. Diego Zocco, Vienna University of Technology
I would like to meet Albert Einstein and spend an evening listening to his favorite music. Bill Christy, System Programmer, Florida Department of Revenue
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fields
Solve a murder mystery with Ada Lovelace! Jette Henderson, Ph.D. student in Computational Sciences, Engineering, and Mathematics, The University of Texas at Austin
Ettore Majorana – I would ask him about his profound contributions to physics and the reason behind his mysterious disappearance in 1938.
Adewale Abiodun Akinfaderin, Graduate Research Assistant, National MagLab
I would want to meet Edwin Hubble and show him all the images captured with his namesake telescope. Westin Kosater, Biochemistry student, Florida State University
Work on a magneto-optics experiment with Michael Faraday.
Madalina Furis, Associate Professor & Materials Science Program Director, The University of Vermont
I would like to have a drink with James Clerk Maxwell.
Kâmil Uğurbil, Director of the Center for Magnetic Resonance Research, University of Minnesota
left field M A G N E T MALL
Make It Better … With a Bitter! The heart of a resistive magnet, the Bitter disk is too beautiful and versatile to be confined to the laboratory.
The building blocks of resistive magnets are Bitter disks. Named after their inventor, Francis Bitter, these round, CD-thick plates of copper alloy are stacked by the hundreds into cylindrical coils that conduct electricity and generate high magnetic fields.
Picture Frame
Your loved ones’ lovely smiles will shine all the brighter surrounded by the metallic glow of a Bitter disk! Just tape the photo to the back of the plate, positioning faces appropriately inside the hole of the disk, attach to the wall and voilà! MLPA12044564 $39.95 €37.22
But to those with a little imagination, these artful medallions have endless other uses. Thanks to their variety of sizes, patterns and colors (silver or copper, which oxides beautifully with age), they inspire applications in the home, the yard, on sports fields and elsewhere. Almost anything can be better with a Bitter!
Bitter Toss Move over, Horseshoes, and make way
Here is some magnet-inspired merchandise we would buy in a heartbeat. Tell us about your own ideas by tweeting us @NationalMagLab. -KC
for the Bitter Toss. Drive a couple of poles into the ground and compete with friends and family to see who will be the first to get a ringer. The smaller your disk, the more points you earn. MLPA90871421 $99.95 €93.12
Pizza Cutter When that frozen pizza comes out of the oven,
there’s just one more step between it and your family’s gaping maws: Divide it into slices! Just roll a small Bitter disk across that cheesy expanse and problem solved. It’s as simple as pizza pie! MLPA01189377 $19.55 €18.21
Squirrel Guard
Keep pests (both furry and scaly) out of the bird feeder by attaching a Bitter disk to the bottom and top. Hours of peaceful bird watching guaranteed! MLPA67725134 $39.95 €37.22
Wind Chime
“Music hath charms to soothe a savage breast, to soften rocks, or bend a knotted oak.” As true today as when that famous line was penned some 300 years ago! Let the gentle jingle-jangle of Bitter disks bandied about in the breeze placate your soul. Hang it on your porch and boost its soothing powers with a cocktail of your choice. MLPA89355002 $88.95 €82.87
Elizabethan Collar
Need to prevent your post-surgical pooch from pulling out stitches? Save the expense (not to mention the canine embarrassment) of those clunky, plastic abominations and outfit Fido with a Bitter disk collar. Just because your furry friend is recovering from surgery doesn’t mean he needs to look like a Conehead! MLPA5699003 $19.55 €18.21
Taco Holder
On your next taco night, wow the family with this impressive taco holder. The perfect receptacle for this corn-based cuisine. Everything tastes better on a Bitter! MLPA82367721 $42.35 €39.46
Earring Make a fashion
statement with a hoop earring made from a small Bitter disk. Those staid designers at Tiffany & Co. can only dream of being so creative! MLPA94200523 $31.35 €29.21 photos by: Stephen Bilenky
Serving Platter
Bitter disks are also called Bitter plates … why not take that literally? A plate rimmed by a glittering Bitter disk (a wee bit of duct tape may be required here) makes an attractive addition to any dinner table. MLPA62349255 $23.95 €22.31
Halo
Have you done something virtuous today? Don’t wait for your inattentive spouse or boss to notice. Crown yourself with a Bitter disk halo so all may know of your noble righteousness. MLPA98330567 $13.55 €12.62
Ca l l 1 - 8 0 0 - N O T - R E A L t o place your order today!
National MagLab Florida State University 600 W. College Ave. Tallahassee, FL 32306
Non-profit Organization U.S. Postage PA I D Tallahassee, FL Permit No. 55
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photo by: Ray Stanyard
Sure, these Bitter disks make for darn good magnets. But we have a few ideas for more creative applications. Join us on page 19 for some inventive fun.
Headquartered in Tallahassee, Florida, The National High Magnetic Field Laboratory is home to some of the world’s strongest and most unique magnets, and belongs to a network of high-field magnet labs around the world offering scientists cutting-edge instruments for their discoveries.
@NationalMagLab The MagLab is supported by the National Science Foundation (DMR – 1157490) and the State of Florida.