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Primal Magnetism

Quantum critical transitions take place at absolute zero and their occurrence can provide fundamental information about the onset of magnetism.  Studying quantum criticality is challenging, however, because we cannot make measurements at absolute zero, and we must rely on less distinct changes in the state of a solid, that occur at slightly higher temperatures.

Strong Interactions Need Not Apply

A new kind of magnetic order has been observed in barium-cobalt iron arsenide high-temperature superconductors by researchers with expertise in growing large single crystals, conducting x-ray and neutron measurements, and calculating electronic structures. Traditional antiferromagnetic order observed, for example, in the copper oxide high-temperature superconductors is driven by strong electron-electron interactions that can result in insulating behavior.

Harvesting Sunlight with Tadpoles and Drumsticks

Scientists have discovered a method to fine-tune the shapes of nanorod photocatalyst particles. These materials accelerate reactions when they are activated by light and their shape affects their behavior. Researchers showed that the photocatalysts, made from tiny amounts of cadmium, sulfur and selenium, will form selectively into shapes that look like either tadpoles or drumsticks depending on the selenium concentration.

Live from the Lab - SPORT Video

Thanks to the innovation of “single particle orientation and rotation tracking” (SPORT), we now can watch the distinctive movements of drug delivering nanoparticles in real time. Nanoparticles have the potential to revolutionize drug delivery.  When these particles interact with cell membranes they move in all sorts of ways.  They spin, they tumble, they move along and through the membrane.  At least that’s what we think.  But what’s really going o

Under Pressure - A Material's Secrets Revealed

Researchers have used pressure as a tool to study the magnetic behavior of a challenging series of materials, RVSb3, where R is a rare-earth.  This series offers a way to study magnetic ordering in materials with a single, unique rare-earth site and it has been studied primarily as a function of temperature. CeVSb3 is the only compound in the family that orders ferromagnetically, that is with all its unpaired electron spins parallel, at low temperatures.

Seeing Order Emerge out of Chaos

Using computer simulations, researchers are able to watch how a random mixture of gold nanoparticles with two different DNA strands as linkers assemble right on their computer screen. The magic starts with just a fraction of the nanoparticles forming a large cluster like a plate of spaghetti and meatballs. Within this random cluster, small ordered regions form and eventually lock together into a large uniform array of particles held together with DNA strands. Using computer simulations they also predict previously unseen structures.

OOPS! That Funny Behavior is Just an Accident, Really.

Iron and copper are both magnetic, but only iron sticks to your refrigerator. That’s because iron is ferromagnetic at room temperature, while copper is paramagnetic. For a material to have two types of magnetism simultaneously at one temperature is uncommon. To have three types simultaneously is exceedingly rare. The alloy NbFe2 is one of those rare materials: at low temperatures it is ferromagnetic, paramagnetic and antiferromagnetic.But why?

Toss in a Little Ruthenium, Apply Pressure and Voilà!

Researchers working to understand high temperature superconductivity in barium-iron-arsenide have discovered that applying pressure affects the material's magnetic and superconducting behavior just as if they had replaced some iron with a little ruthenium. To better quantify and understand the similarities of changing pressure versus ruthenium concentration, they made Ba(Fe1-xRux)2As2 with varying amounts (x) of ruthenium and studied each concentration as a function of pressure and temperature.


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