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Spectroscopic and magnetic response in excitonic insulators

ORAL

Abstract

Excitonic insulators (EIs) are a strongly correlated phase of matter whose ground state is a coherent superposition of correlated electron-hole pair states. These EI states are distinct from superconductors due to the charge neutrality of excitons, as opposed to Cooper pairs. Moreover, the EI phase is also different from superfluidity, due to the presence of the crystalline lattice. It is a challenge to identify experimental signatures that distinguish an EI phase from a conventional band insulator (BI) phase; both exhibit a gapped quasiparticle bandstructure.

In this talk, we discuss recent theoretical work in ab-initio spectroscopic and magnetic response signatures to separate the BI phase from the EI phase in the BCS limit. DFPT with a perturbing magnetic field and GW-BSE with a DFT starting point may be employed for the magnetic response and optical absorption, respectively, of the BI. Elsewhere, we may combine GW-BSE analysis with BCS theory to study the EI condensate.

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Presenters

  • James Wu

    University of California, Berkeley and Lawrence Berkeley National Laboratory

Authors

  • James Wu

    University of California, Berkeley and Lawrence Berkeley National Laboratory

  • Fang Zhang

    University of California, Berkeley and Lawrence Berkeley National Laboratory, University of California, Berkeley

  • Gurjyot Sethi

    University of California, Berkeley and Lawrence Berkeley National Laboratory, University of California, Berkeley

  • Steven G Louie

    University of California, Berkeley, University of California, Berkeley and Lawrence Berkeley National Lab, University of California, Berkeley and Lawrence Berkeley National Laboratory, Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, Department of Physics, University of California at Berkeley, Berkeley, CA, USA and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA