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Dr. Grigory Bednik (UC Santa Cruz)

Feb 20, 2020 - 4:10 PM
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Speaker: Dr. Grigory Bednik (UC Santa Cruz)

Title: New phases emerging from Dirac semimetals

Abstract: Dirac semimetals are a new class of gapless materials, whose low-energy spectrum can be described by linear Dirac dispersion. They contain Dirac points, whose existence is protected by rotational symmetry. In the first part of my talk, I am planning to demonstrate that by breaking rotational symmetry, Dirac semimetal can be deformed into topological crystalline insulator, in such a way that the Dirac semimetal phase is a critical point between two phases of topological crystalline insulators with the opposite mirror Chern numbers. This picture makes it possible to see that surface states in Dirac semimetals always terminate at the Dirac points despite lacking topological protection. In the second part of my talk, I am planning to discuss possible magnetic instabilities in Dirac semimetals. I explain the fact that Dirac semimetals tend to be antiferromagnetic rather than ferromagnetic.