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The collective modes of the charge density wave (CDW) in (TaSe<sub>4</sub>)<sub>2</sub>I studied with time-resolved x-ray scattering

POSTER

Abstract

(TaSe4)2I (TSI) is a quasi-1D charge-density-wave (CDW) material and Weyl semimetal that has attracted much recent interest due to recent claims of the experimental observation of an axionic insulator phase. We studied the CDW collective modes of TSI using time-resolved x-ray scattering at the LCLS and SACLA free electron laser (FEL) facilities. We observe sub-THz oscillations at the CDW sidebands, and assign a component at 0.11 THz as an amplitude mode of the CDW. We analyze the amplitude mode signal with a coupled-mode Ginzburg-Landau model and find excellent agreement with experiment. In addition to the amplitude mode signal we also observe low-frequency dispersive signal components in the vicinity of the CDW sidebands, which we interpret as signals arising from photoexcited CDW phase modes.

Presenters

  • Ryan A Duncan

    Stanford University

Authors

  • Ryan A Duncan

    Stanford University

  • Quynh L Nguyen

    University of Colorado, Boulder

  • Gal Orenstein

    Stanford, Stanford University

  • Gilberto De La Pena

    SLAC - Natl Accelerator Lab, University of Illinois at Urbana-Champaign

  • Viktor Krapivin

    Stanford University, Stanford Univ

  • Yijing Huang

    Stanford University, Stanford Univ

  • Chance Ornelas-Skarin

    Stanford University, Stanford University/SLAC

  • Soyeun Kim

    University of Illinois at Urbana-Champai, Stanford University

  • Simon L Bettler

    University of Illinois at Urbana-Champaign

  • Oscar Qu

    University of Illinois

  • Peter Abbamonte

    University of Illinois at Urbana-Champai, University of Illinois at Urbana-Champaign

  • Daniel P Shoemaker

    University of Illinois at Urbana-Champaign, University of Illinois

  • Samuel W Teitelbaum

    Arizona State University, ASU

  • Fahad Mahmood

    UIUC, University of Illinois Urbana-Champaign, University of Illinois at Urbana-Champaign, University of Illinois Urbana Champaign, University of Illinois

  • David A Reis

    Stanford Univ, Stanford PULSE Institute

  • Mariano Trigo

    SLAC - Natl Accelerator Lab