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Events on Thursday, March 2nd, 2017

R. G. Herb Condensed Matter Seminar
Spiraling energy dispersion of arc states in Weyl semimetals
Time: 10:00 am
Place: Chamberlin 5310
Speaker: Anton Andreev, University of Washington
Abstract: Weyl semimetals are recently discovered materials in which the
valence and conduction bands touch at isolated points (Weyl nodes)
in the Brillouin zone. This gives rise to unusual electronic properties
of these materials. In particular, Weyl semimetals host peculiar
surface electron states whose Fermi lines have the form of open arcs.
I will show that static electric fields that are necessarily present
near the crystal surface result in a spiraling structure of Fermi arcs.
The winding angle of the spiral is controlled by the chirality of the Weyl
node and the magnitude of the surface potential. I will also discuss
magnetoresistance of a pn-junction in a Weyl semimetal.
Host: Levchenko
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Astronomy Colloquium
"The Internal Structure of Interstellar Filaments in the Southern Milky Way"
Time: 3:30 pm - 5:00 pm
Place: 4421 Sterling Hall, Coffee and Cookies at 3:30 PM. Talk starts 3:45 PM
Speaker: Audra Hernandez, UW Madison Astronomy Dept
Abstract: Is all Galactic star formation concentrated within filamentary structures inside molecular clouds? High resolution observations have shown that filamentary interstellar clouds are ubiquitous throughout the interstellar medium. These filaments exist over a range of spatial scales, from parsec regions containing young stellar activity, to the multi-parsec scales of giant molecular clouds. Although infrared observations have provided high-resolution images of star-forming clouds, they are limited by their two-dimensional nature. The only way to assess the kinematical natures of thee filaments is through spectroscopic radio observations. While it is clear that stars form within the desist regions of the interstellar medium, one of the main goals of modern astrophysics is to understand how the properties of interstellar filaments influence the star-formation process. I will begin with a review of the recent and exciting studies on multi-scale molecular filaments. Finally, I will discuss my ongoing research on probing the internal structure of interstellar molecular filaments within the Southern Galactic plane with recent multi-line large-scale spectroscopic molecular surveys.
Host: Astronomy Dept
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