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STM study of electron-phonon many-body interplay in a frustrated paramagnet

ORAL

Abstract

We use state-of-the-art scanning tunneling microscopy/spectroscopy to discover unusual electronic coupling to flat-band phonons in a layered kagome paramagnet, CoSn. We image the kagome structure with unprecedented atomic resolution and observe the striking bosonic mode interacting with dispersive kagome electrons near the Fermi surface. At this mode energy, the fermionic quasi-particle dispersion exhibits a pronounced renormalization, signaling a giant coupling to bosons. Through the self-energy analysis, first-principles calculation, and a lattice vibration model, we present evidence that this mode arises from the geometrically frustrated phonon flat-band, which is the lattice bosonic analog of the kagome electron flat-band. Our findings provide the first example of kagome bosonic mode (flat-band phonon) in electronic excitations and its strong interaction with fermionic degrees of freedom in kagome-net materials.

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Presenters

  • Yuxiao Jiang

    Princeton University

Authors

  • Yuxiao Jiang

    Princeton University

  • Jiaxin Yin

    Princeton University, Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Department of Physics, Princeton University

  • Nana Shumiya

    Princeton University

  • Sougata Mardanya

    Physics, National Cheng Kung University, Department of Physics, Indian Institute of Technology Kanpur, India

  • Songtian Zhang

    Princeton University, Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Department of Physics, Princeton University

  • Zahid Hasan

    Princeton University, Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University

  • Hechang Lei

    Renmin university of China, Renmin University of China, Boston College, International Center for Quantum Materials, Peking University