This Week at Physics

<< December 2017 >>
Sun Mon Tue Wed Thu Fri Sat
   1   2 
 3   4   5   6   7   8   9 
 10   11   12   13   14   15   16 
 17   18   19   20   21   22   23 
 24   25   26   27   28   29   30 
Add an Event Edit This Event

This Week at Physics

<< Spring 2017 Fall 2017 Spring 2018 >>
Subscribe your calendar or receive email announcements of events

Event Number 4654

  Wednesday, December 6th, 2017

R. G. Herb Condensed Matter Seminar
Unconventional interactions between 2D excitons and their environment
Time: 10:00 am
Place: 5310 Chamberlin Hall
Speaker: Dr. Andrey Klots , Vanderbilt University
Abstract: Excitons and excitonic complexes (EC) are solid-state analogs of atoms and<br>
molecules. Simple hydrogen-like states can be studied using a plain Schrodinger<br>
equation. However, when an EC is coupled to a medium with a frequency- or<br>
momentum-dependent dielectric function, "(!; q), the quantum-mechanical de-<br>
scription of such system becomes less trivial. The _rst part of this talk describes<br>
a treatment of many-body states of charged particles coupled to a frequency-<br>
dependent medium. I will show that the problem of dynamically screened ECs<br>
can be formally reduced to a simple problem of an EC in an e_ectively static<br>
medium. The environment's e_ective dielectric constant `perceived' by ECs de-<br>
pends on the symmetries of EC wavefunctions and their binding energies. This<br>
approach is applicable to individual electrons as well as to large many-body com-<br>
plexes. Predictions of environmental e_ects on EC binding were experimentally<br>
veri_ed using neutral, charged and defect-bound excitons in monolayer WS2<br>
screened by liquid, metallic and semiconducting environments.<br>
In the second part of the talk I will show that coupling of excitons to some<br>
metamaterials with momentum-dependent dielectric functions, "(~k), allows cre-<br>
ation of ultrarelativistic excitons with high momenta. As a result of the Lorentz<br>
contraction, one can observe transient one-dimensional relativistic excitons in<br>
two-dimensional graphene.<br>
Host: Lev Ioffe
Add this event to your calendar
©2013 Board of Regents of the University of Wisconsin System