BEGIN:VCALENDAR VERSION:2.0 PRODID:Data::ICal 0.22 BEGIN:VEVENT DESCRIPTION:Vidya Madhavan\, University of Illinois at Urbana-Champaign\n\n
\n Electrons in free space have a well-defined mass. Recently\, a new c lass of materials called topological insulators were discovered\, where th e low energy electrons have zero mass. In fact\, these electrons can be described by the same massless Dirac equation that is used to descr ibe relativistic particles travelling close to the speed of light. In this talk I will describe our recent experimental and theoretical investigatio ns of a class of materials called Topological Crystalline Insulators (TCIs ) [1]. TCIs are recently discovered materials [2\,3] where topology and cr ystal symmetry intertwine to create linearly dispersing Fermions similar t o graphene. To study this material we used a scanning tunneling microscope [3\,4\,5]. With the help of our high-resolution data\, I will show how ze ro-mass electrons and massive electrons can coexist in the same material. I will discuss the conditions to obtain these zero mass electrons as well the method to impart a controllable mass to the particles and show how our studies create a path to engineering the Dirac band gap and realizing int eraction-driven topological quantum phenomena in TCIs.
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\n [1] L. Fu\, Topological Crystalline Insulators. Phys. Rev. Lett. 106\, 106802 (2011).
\n\n [2] T. H. Hsieh et al.\, Topolo gical crystalline insulators in the SnTe material class. Nat.Commun. < /em>3\, 982 (2012).
\n\n [3] Y. Okada\, et al.\, Observation of Dira c node formation and mass acquisition in a topological crystalline insulat or\, Science 341\, 1496-1499 (2013)
\n\n [4] Ilija Zeljkovi c\, et al.\, Mapping the unconventional orbital texture in topological cry stalline insulators\, Nature Physics 10\, 572&ndash\;577 (2014) p>\n
\n [5] Ilija Zeljkovic\, et al.\, Dirac mass generation from crysta l symmetry breaking on the surfaces of topological crystalline insulators\ , arXiv:1403.4906
\n DTSTART:20141205T203000Z LOCATION:Physics Building\, Room 204 SUMMARY:Massless and Massive Electrons: Relativistic Physics in Condensed M atter Systems END:VEVENT END:VCALENDAR