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Signatures of excitonic insulating phase in a monolayer transition metal dichalcogenide

ORAL

Abstract

An excitonic insulator (EI) is a condensed many-body state of correlated electron-hole pairs, analogous to a superconductor with Cooper pairs. Despite numerous experimental indications of possible EI ground states in various materials, its definitive experimental observation and microscopic nature remains elusive. Previous theoretical studies often rely on simplified models that may not capture the full complexity of different systems. Here, we develop a first-principles framework that enables the determination of electron-hole pairing order parameters and single-particle properties at finite temperatures. We apply our approach to a prototypical two-dimensional EI candidate material: monolayer 1T'-MoS2. Our results reveal that its ground state exhibits excitonic insulating behaviour with unique symmetry properties, and we identify several spectroscopic signatures of the EI phase that can be experimentally verified. We anticipate that our methods and findings have broad applicability for understanding excitonic condensations in materials with strong electron-hole correlations.

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Presenters

  • Fang Zhang

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

Authors

  • Fang Zhang

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

  • Jiawei Ruan

    UC Berkeley, Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory

  • 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