New frontiers for topological semimetals

Event Dates: 

Thursday, September 28, 2017 - 12:00pm

CTQM Seminar Type: 

  • Related Seminar Series

Speaker Name(s): 

Barry Bradlyn

Speaker Affiliation(s): 


Abstract, Event Details: 

Following their insulating counterparts, topological semi-metals have attracted much theoretical and experimental interest. Weyl and Dirac semimetals have recently been theoretically predicted and experimentally observed; both display topologically protected Fermi-arc surface states, as well as large negative magnetoresistance due to the ``chiral anomaly’’. In this talk, I will go beyond Weyl and Dirac fermions to discuss how non-symmorphic crystal symmetries can stabilize exotic topological band degeneracies in spin-orbit coupled materials. Some notable consequences of these degeneracies are the presence of Fermi arcs in non-Weyl systems, the fermionic spin-1 generalization of a Weyl fermion, and the existence of Dirac lines. I will pay particular attention to experimentally realizable material candidates. Finally, I will show how the intricate patterns of connected energy bands implied by these large degeneracies also lends new insights into the physics of topological insulators.