Evidence for a phononic origin of the charge density waves in 2H-TaS2 and other transition metal dichalcogenides

POSTER

Abstract

The underlying mechanism of charge density waves (CDW) is still an unresolved problem, both in general and in the specific scope of transition metal dichalcogenides (TMD). Here we report an Angle-Resolved Photoemission Spectroscopy (ARPES) study of the incommensurate CDW order in the 2H (trigonal prismatic) polytype of TaS2. In this prototype two-dimensional system, we observed pronounced temperature independent, yet moment dependent many-body renormalizations of the electronic band dispersion. Detailed analysis revealed that these signatures can be related to phonon modes. Similar observations reported for TaSe2 and NbSe2 suggests this phononic origin can be a general phenomenon for TMDs. Furthermore, the persistence of these renormalizations was observed above CDW transition temperature corroborating pre-reported pseudogap effect. Also, the introduction of strong electron-phonon interactions to a tight binding model led to a successful explanation of a multitude of behaviors generally exhibited by CDW s in TMDs as well.

Presenters

  • Kapila Wijayaratne

    Department of Physics, University of Virginia

Authors

  • Kapila Wijayaratne

    Department of Physics, University of Virginia

  • Junjing Zhao

    Department of Physics, University of Virginia, Physics, University of Virginia

  • Christos Malliakas

    Department of Chemistry, Northwestern University, Northwestern University

  • Duck Young Chung

    Materials Science Division, Argonne National Laboratory, Materials Science Division, Argonne National Lab, Argonne National Laboratory

  • Mercouri Kanatzidis

    Department of Chemistry, Northwestern University, Chemistry, Northwestern University, Chemistry, Northwestern University, Evanston, IL 60208, Northwestern University, Materials Science Division, Argonne National Laboratory, Argonne National Laboratory

  • Utpal Chatterjee

    Department of Physics, University of Virginia, Physics, University of Virginia