Bulletin of the American Physical Society
APS March Meeting 2018
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session P44: Topological Protection in Correlated Electron Systems 2
2:30 PM–5:30 PM,
Wednesday, March 7, 2018
LACC Room: 504
Sponsoring Unit: DCMP
Chair: Saurabh Maiti, University of Massachusetts Amherst
Abstract: P44.00011 : Excitonic instability in optically-pumped three-dimensional Dirac materials*
4:30 PM–4:42 PM
We discuss the possibility of achieving a transient excitonic condensate in optically-pumped three-dimensional (3D) DMs, such as Dirac and Weyl semimetals, described by non-equilibrium chemical potentials for photoexcited electrons and hole. We find that for pumped 3D DMs with screened Coulomb potential two possible excitonic phases exist, an excitonic insulator phase and the charge density wave phase originating from intranodal and internodal interactions, respectively. In the pumped case, the critical coupling for excitonic instability vanishes; therefore, the two phases coexist for arbitrarily weak coupling strengths. The excitonic gap in the charge density wave phase is always the largest one. We present the signatures of the transient excitonic condensate that could be probed by scanning tunneling spectroscopy, photoemission and optical conductivity measurements. Finally, we provide estimates of critical temperatures and excitonic gaps for existing and hypothetical 3D DMs.
*Work at LANL was supported by USDOE LDRD. This work was supported by Villum Center for Dirac Materials
ERC-DM-32031, KAW. We also acknowledge support from Dr. Max Rossler, the Walter Haefner Foundation and the ETH Zurich Foundation.
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