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Time-resolved low energy electrodynamics of Ta<sub>2</sub>NiSe<sub>5</sub> : search for optical signatures of the excitonic insulator phase

ORAL

Abstract

The excitonic insulator (EI) is an interesting phase of matter where electron-hole pairs form a Bose-Einstein-like condensate. We report the low energy dynamics of Ta2NiSe5, a candidate EI material with Tc = 328 K. This is accomplished using ultrafast near-infrared pump-broadband THz probe spectroscopy. Our broadband probe enables simultaneous measurement of electron and phonon dynamics relevant to the EI state. We will compare the dynamics in with its sister compound Ta2NiS5, an isoelectric semiconductor, with a view towards disentangling dynamics associated with conventional semiconducting behavior (and the monoiclinic-orthorhombic structural transition) from pure EI order parameter dynamics.

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Presenters

  • Sheikh Rubaiat Ul Haque

    Physics, University of California San Diego

Authors

  • Sheikh Rubaiat Ul Haque

    Physics, University of California San Diego

  • Junbo Zhu

    Massachusetts Institute of Technology MIT, Physics, Massachusetts Institute of Technology

  • Gufeng Zhang

    Physics, University of California San Diego, Department of Physics, University of California, San Diego

  • Mustafa G Ali

    Physics, University of California San Diego

  • Kelson Kaj

    University of California San Diego, Physics, University of California San Diego, Department of Physics, University of California, San Diego, University of California, San Diego

  • Yuan Zhang

    Physics, University of California San Diego

  • Joseph Checkelsky

    Massachusetts Institute of Technology, Department of Physics, Cambridge, MA, USA, Massachusetts Institute of Technology MIT, Department of Physics, Massachusetts Institute of Technology, Massachusetts Institute of Technology, Physics, Massachusetts Institute of Technology

  • Richard Averitt

    University of California, San Diego, University of California San Diego, UC San Diego, Physics, University of California San Diego, Department of Physics, University of California, San Diego, University of California