BEGIN:VCALENDAR VERSION:2.0 PRODID:Data::ICal 0.22 BEGIN:VEVENT DESCRIPTION:Adam Kaminski\, Iowa State and Ames Lab.\n\n
The discovery of D irac fermions in graphene has inspired a search for Dirac and Weyl semimet als in three dimensions thereby making it possible to realize exotic phase s of matter first proposed in particle physics. Such materials are charact erized by the presence of nontrivial quantum electronic states\, where the electron&rsquo\;s spin is coupled with its momentum and Fermi surfaces ar e no longer closed contours in the momentum space\, but instead consist of disconnected arcs. This opens up the possibility for developing new devic es in which information is stored and processed using spin rather than cha rge. Such platforms may significantly enhance the speed and energy efficie ncy of information storage and processing. In this talk we will discuss th e electronic properties of several of newly discovered tellurium based top ological quantum materials. In WTe2 we have observed a topologi cal transition involving a change of the Fermi surface topology (known as a Lifshitz transition) driven by temperature. The strong temperature-depen dence of the chemical potential that is at the heart of this phenomenon is also important for understanding the thermoelectric properties of such se mimetals. In a close cousin\, MoTe2\, by using high-resolution laser based Angle Resolved Photoemission Spectroscopy (ARPES) we identify Weyl points and Fermi surface arcs\, showing a new type of topological Wey l semimetal with electron and hole pockets that touch at a Weyl point. I w ill also present evidence for a new topological state in PtSn4\ , that manifests itself by presence of set of extended arcs rather than Di rac points\, and so far is not yet understood theoretically. These results open up new directions for research aimed at enhancing topological respon siveness of new quantum materials.
\n DTSTART:20180330T193000Z LOCATION:Physics Building\, Room 204 SUMMARY:Chasing Relativistic Electrons in Topological Quantum Materials END:VEVENT END:VCALENDAR