Events at Physics |
Events on Thursday, November 12th, 2009
- R. G. Herb Condensed Matter Seminar
- Oxide Nanoelectronics
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Jeremy Levy, University of Pittsburgh
- Abstract: Electronic confinement at nanoscale dimensions remains a central means of science and technology. In this talk, I will describe a new method for producing extreme nanoscale electronic confinement at the interface between two separately insulating oxides, LaAlO3 and SrTiO3. Using an approach reminiscent of the popular toy "Etch-a-Sketch", we scan an electrically biased probe on the surface of this heterostructure to create nanoscale conducting islands, nanowires, tunnel junctions and field-effect transistors at the interface. The smallest feature size approaches one nanometer. These structures are created in ambient conditions at room temperature, and can be erased and rewritten repeatedly. At low temperatures, a variety of quantum phases have been observed, including integer and fractional quantum Hall states and superconductivity. This new, on-demand nanoelectronics platform has the potential for widespread scientific and technological exploitation.
This work is supported by the National Science Foundation, Defense Advanced Research Projects Agency, Army Research Office and Air Force Office of Scientific Research. - Host: Mark Rzchowski
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Galactic cosmic ray anisotropy : origin and implications and the role of IceCube
- Time: 4:00 pm
- Place: 5310 Chamberlin
- Speaker: Paolo Desiati, University of Wisconsin at Madison
- Abstract: The assumed isotropy of galactic cosmic rays has been topic of investigation since the seventies, when an O(10^-3 - 10^-4) anisotropy in arrival direction has been observed for the first time. The wide energy range of this observations (from tens of GeV to hundreds of TeV) has raised questions on the origin of this phenomenon. While we can generically claim that the responsible of this anisotropy is to be connected to the structure of the Local Interstellar Medium, and specifically to the Local Interstellar Magnetic Field (within about 0.1-1.0 pc ~ 20,000 - 200,000 AU), we still suffer from the lack of knowledge of the properties of our local environment. Only recently, with the observation of O(10-30 degrees) excess of cosmic rays by MILAGRO and with the first high statistics observation of the southern sky by IceCube, the topic is gaining renewed attention. The possibility that the ~100's TeV galactic cosmic ray anisotropy might be connected to the blast from a nearby supernova, in connection with the anomalies in the observed positron fraction and electron spectrum is very appealing and will be discussed.
- Host: Michael Ramsey-Musolf
- Introductory Graduate Seminar
- Phenomenology
- Time: 5:30 pm
- Place: 2223 Chamberlin Hall
- Speaker: Barger, Everett, Halzen, Han, Petriello, University of Wisconsin Department of Physics