## "Properties of Topological semimetals: Chiral magnetic effect and instability under magnetic field"

**Speaker:**Xi Dai, Hong Kong University of Science and Technology

**When:**December 15, 2017 (Fri), 11:00AM to 12:00PM (add to my calendar)

**Location:**SCI 352

**Hosted by:**Wanzheng Hu

*This event is part of the Condensed Matter Theory Seminar Series. *

In the present talk, I will introduce two important physical properties of topological semimetals. The first one is the chiral magnetic effect, which is the direct consequence of the presence of Weyl points in the band structures. I will introduce that the chiral magnetic effect can be detected by its coupling to certain phonon modes, which behave like pseudo scalars under point group transformations. Such coupling can generate resonance between the intrinsic plasmon oscillation and the corresponding phonon modes, leading to dramatic modification of the optical response by the external magnetic field. The second one is the instability of topological semimetal phase under strong magnetic field. In Dirac semi-metal, the quantum limit can be easily reached under the magnetic field leading to two types of phase instability caused by the high degeneracy of the topological zeroth Landau bands (LBs), namely the charge density wave (CDW) phase and polarized nematic phase formed by exciton condensation. We also propose that both the DC transport measurement and Raman scattering can be used to distinguish the above two phases.