Events at Physics
Events on Thursday, April 8th, 2010
- R. G. Herb Condensed Matter Seminar
- Spin electronics for materials spectroscopy
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Christoph Boehme, University of Utah
- Abstract: In semiconductors with weak spin-orbit coupling, spin-selection rules allow electron spins and nuclear spins to influence electrical and optical material properties. Such spin-dependent processes enable a number of applications ranging from readout of spin quantum computers and spin-electronic devices to semiconductor spin spectroscopy. The latter is of great importance for understanding the role that spins play for efficiencies of solar cells, light emitting diodes and other electronic devices. In this talk I will discuss our recent progress on the development of a spin-selection rule based coherent spin spectroscopy and I will summarize our research-activities and -results using this technique. I will then discuss in detail an experiment demonstrating the control of the electric current in organic light emitting diodes by spin-beat oscillations of Coulomb-coupled charge carriers pairs. The beat oscillations are due to a difference of the local magnetic hyperfine fields caused by a bath of hydrogen nuclear spins in the vicinity of the charge carrier pairs. The observation of this effect provides insights into how nuclear spins in organic semiconductors influence conductivity and electroluminescence.
- Host: Mark Eriksson
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- The Chiral Magnetic Effect and local parity violation at RHIC
- Time: 4:00 pm
- Place: 4274 Chamberlin
- Speaker: Dmitri Kharzeev, Brookhaven National Laboratory
- Abstract: will address the role of chiral symmetry and parity invariance in the properties of hot and dense quark-gluon matter. The possibility of parity-odd effects in this matter will be discussed. Local parity violation can manifest itself in heavy ion collisions at RHIC through the spatial separation of positive and negative particles with respect to the reaction plane. The charge separation induces the electric dipole moment of the produced hot quark-gluon matter; it stems from the interplay of strong magnetic field in the early stage of the heavy ion collision and the presence of topological configurations in hot matter ("the chiral magnetic effect"). There is a recent experimental evidence for local parity violation at RHIC. The effect has interesting implications for the cosmology of the Early Universe, and has analogs in condensed matter physics (quantum wires, graphene, and topological insulators), and in astrophysics (particle acceleration in cosmic strings).