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Events on Thursday, February 21st, 2013

R. G. Herb Condensed Matter Seminar
Spin-Orbit Tuned Ground States in Single-Crystal Iridates
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Gang Cao, University of Kentucky, Lexington
Abstract: The most profound result of the spin-orbit interaction (SOI) on iridates is the Jeff=1/2 insulating state, a new quantum state that represents the novel physics in the 5d-based systems. The SOI vigorously competes with Coulomb interactions, non-cubic crystal electric field and Hund's rule coupling, and critically biases their mutual competition to stabilize ground states with exotic behavior, which sharply contrasts with traditional models. Indeed, two conspicuous phenomena are commonly observed among layered iridates: (1) the Jeff = 1/2 insulating state, and (2) relatively high magnetic ordering temperatures and complex magnetic states that are not predicted by existing models. In this talk, we review the underlying physical properties of the layered iridates, and report results of our study that emphasizes spin-orbit-tuned ground states stabilized by chemical doping, application of pressure and magnetic field; these weak perturbations are capable of directly reducing the SOI so as to rebalance comparable interactions to generate a rich phase diagram of strongly competing ground states controlled by the SOI.
Host: Perkins
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Astronomy Colloquium
Evolution of Galaxy Populations in the Most Distant Galaxy Clusters
Time: 3:30 pm - 5:00 pm
Place: 4421 Sterling Hall
Speaker: Mark Brodwin, University of Missouri- Kansas City
Abstract: I will describe the emerging evidence for an epoch of significant growth of cluster galaxies at z ~ 1.5, about 10 billion years in the past. This evidence rules out the (overly) simplistic galaxy formation models that seem to fit the data at later times (ie. at z < 1). New measurements of rapid evolution in a number of critical probes of the growth of cluster galaxies aEuro" including a census of their stars, the colors of those stars, and the rates of star formation, mergers and black hole activity aEuro" all suggest the z ~ 1.5 era is a very active one in the formation and assembly of massive cluster galaxies.
Host: Christi Tremonti
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