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Surprising Control over Photoelectrons from a Topological Insulator

By Guest PostMarch 24, 2013Science3d topological insulators, alessandra lanzara, als, angle resolved, arpes, atoms, berkeley lab, chris jozwiak, data collection, dirac point, dung hai lee, electronic states, energy momentum diagrams, field of spintronics, flight analyzer, german, graphene, incident light, laser beam, magnetic surface, momentum space, p polarized, photoelectrons, photoemission spectroscopy, quantum computing, s polarization, s polarized, senkrecht, spin polarized, spin time, steve louie, strange crystalline materials, tis, topological insulator, university of california, zahid hussain

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.

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. (more…)

Sleep consolidates memories for competing tasks

By Guest PostMarch 24, 2013Nature, Scienceavian, brain, brain function, consolidate learning, daniel margoliash, development in birds, excellent model, formation, howard nusbaum, mammalian brains, sleep, stable memories, starlings, timothy brawn, university of chicago

Sleep plays an important role in the brain’s ability to consolidate learning when two new potentially competing tasks are learned in the same day, research at the University of Chicago demonstrates.

Other studies have shown that sleep consolidates learning for a new task. The new study, which measured starlings’ ability to recognize new songs, shows that learning a second task can undermine the performance of a previously learned task. But this study is the first to show that a good night’s sleep helps the brain retain both new memories. (more…)

Tooth pushes back modern monkeys’ first ancestor three million years

By Guest PostMarch 23, 2013Nature, Scienceancestor, andrew hill, anthropologists, baboons, basal african monkeys, central kenya, cercopithecid family, christopher c gilbert, city, clayton stephenson, family victoriapithecidae, great rift valley, hunter college, james b rossie, lineage, macaques, million years ago, modern african monkeys, monkey family tree, new york, old world monkey, sallye stephenson, schwartz family foundation, stony brook university, teeth, tugen hills, vervet monkeys, yale university

The ancestor of all modern African monkeys was alive 3 million years earlier than previously thought and coexisted with members of a now-extinct branch of the monkey family tree, according to new evidence from anthropologists.

“We pushed back the origin of modern monkeys by a huge chunk of time,” said anthropologist Andrew Hill of Yale University, the senior researcher on the project. “This means there are all sorts of things we can think about. You can start to look at animal interactions that might have taken place.” (more…)

Researchers Solve Riddle of What Has Been Holding Two Unlikely Materials Together

By Guest PostMarch 23, 2013Sciencebi2te3, bismuth telluride, bonds, electricity, electronics, gaas, gallium arsenide, heat into electricity, houston dycus, james lebeau, jonathan pierce, molecules, north Carolina, rama venkatasubramanian, rti international, state university, super x, thin films, van der waals, weak electrical forces

For years, researchers have developed thin films of bismuth telluride (Bi2Te3) – which converts heat into electricity or electricity to cooling – on top of gallium arsenide (GaAs) to create cooling devices for electronics. But while they knew it could be done, it was not clear how – because the atomic structures of those unlikely pair of materials do not appear to be compatible. Now researchers from North Carolina State University and RTI International have solved the mystery, opening the door to new research in the field.

“We’ve used state-of-the-art technology to solve a mystery that has been around for years,” says Dr. James LeBeau, an assistant professor of materials science and engineering at NC State and co-author of a paper on the research. “And now that we know what is going on, we can pursue research to fine-tune the interface of these materials to develop more efficient mechanisms for converting electricity to cooling or heat into electricity. Ultimately, this could have applications in a wide range of electronic devices.” (more…)

Planck Mission Brings Universe into Sharp Focus

By Guest PostMarch 22, 2013Sciencecosmic microwave, dark matter, expansion of universe, planck data, planck mission, space mission

PASADENA, Calif. — The Planck space mission has released the most accurate and detailed map ever made of the oldest light in the universe, revealing new information about its age, contents and origins. (more…)

A Telescope at the Bottom of the World

By Guest PostMarch 21, 2013Scienceantarctic plateau, interstellar space, molecular clouds, plateau observatory, star forming nebulae, terahertz telescope

Alone in a wilderness of snow and ice, 600 miles from the Earth’s South Pole, a solitary telescope watches the stars, searching for the origins of the colorful nebulae in which stars are born.

The brilliantly colored, sweeping nebulae featured on magazine covers and posters lining museum exhibits are the birthplaces and cradles of the stars in our galaxy. (more…)

Curiosity Mars Rover Sees Trend in Water Presence

By Guest PostMarch 20, 2013Sciencealuminum, apxs, arizona state university, basalt like proportions, calibration target, curiosity mars rover, dan, drilled rock, evidence, hydrated minerals, iron, iron bearing rocks, jim bell, knorr rock, magnesium, mars, mast camera, mastcam, maxim litvak, melissa rice, mudstone rock, NASA, silicon, trend, veins, water bearing minerals, water presence, yellowknife bay

THE WOODLANDS, Texas – NASA’s Mars rover Curiosity has seen evidence of water-bearing minerals in rocks near where it had already found clay minerals inside a drilled rock.

Last week, the rover’s science team announced that analysis of powder from a drilled mudstone rock on Mars indicates past environmental conditions that were favorable for microbial life. Additional findings presented on March 18 at a news briefing at the Lunar and Planetary Science Conference in The Woodlands, Texas, suggest those conditions extended beyond the site of the drilling. (more…)

Long Predicted Atomic Collapse State Observed in Graphene

By Guest PostMarch 19, 2013Sciencealex zettl, andrey shytov, artificial atomic nuclei, atomic collapse behavior, atomic collapse state, berkeley lab, calcium dimers, dillon wong, electrical conductor, electronic devices, electronic resonance, electrons, energy, graphene, holy grail, michael crommie, nuclear physics, nucleus, predictions, quantum mechanical phenomenon, relativistic quantum mechanics, roland kawakami, scanning tunneling microscope, smoking gun, Space, stable circular orbits, stm, stm spectroscopy, ultra high vacuum, ultrafast transistors, william regan, yang wang

Berkeley Lab researchers recreate elusive phenomenon with artificial nuclei

The first experimental observation of a quantum mechanical phenomenon that was predicted nearly 70 years ago holds important implications for the future of graphene-based electronic devices. Working with microscopic artificial atomic nuclei fabricated on graphene, a collaboration of researchers led by scientists with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley have imaged the “atomic collapse” states theorized to occur around super-large atomic nuclei.

“Atomic collapse is one of the holy grails of graphene research, as well as a holy grail of atomic and nuclear physics,” says Michael Crommie, a physicist who holds joint appointments with Berkeley Lab’s Materials Sciences Division and UC Berkeley’s Physics Department. “While this work represents a very nice confirmation of basic relativistic quantum mechanics predictions made many decades ago, it is also highly relevant for future nanoscale devices where electrical charge is concentrated into very small areas.” (more…)

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