Semi-Dirac Fermions in a Topological Metal

ORAL

Abstract

Topological semimetals with massless Dirac and Weyl fermions represent the forefront of quantum materials research. In two dimensions, a peculiar class of fermions that are massless in one direction and massive in the perpendicular direction was predicted fifteen years ago. These highly exotic quasiparticles – the semi-Dirac fermions – ignited intense theoretical interest but remain undetected. Using magneto-optical spectroscopy, we demonstrate the defining feature of semi-Dirac fermions – B2/3 scaling of Landau levels – in a prototypical nodal-line metal ZrSiS. In topological metals, including ZrSiS, nodal-lines extend the band degeneracies from isolated points to lines, loops or even chains in the momentum space. With ab initio calculations and theoretical modeling, we pinpoint the observed semi-Dirac spectrum to the crossing points of nodal-lines in ZrSiS. Crossing nodal-lines exhibit a continuum absorption spectrum but with singularities that scale as B2/3 at the crossing. Our work sheds light on the hidden quasiparticles emerging from the intricate topology of crossing nodal-lines.

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Presenters

  • Yinming Shao

    • Columbia University

Authors

  • Yinming Shao

    • Columbia University

  • Seongphill Moon

    • National High Magnetic Field Laboratory

  • Alexander N Rudenko

    • Radboud University

  • Jie Wang

    • Harvard University

  • Mykhaylo Ozerov

    • National High Magnetic Field Laboratory

  • David E Graf

    • Florida State University
    • National High Magnetic Fields Laboratory, Florida State University
    • National High Magnetic Field Laboratory, Florida State University

  • Zhiyuan Sun

    • Tsinghua University
    • Harvard University
    • State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China

  • Raquel Queiroz

    • Columbia University

  • Seng Huat Lee

    • Pennsylvania State University

  • Yanglin Zhu

    • Pennsylvania State University

  • Zhiqiang Mao

    • Pennsylvania State University
    • Pennslyvania State University

  • Mikhail I Katsnelson

    • Radboud University Nijmegen
    • Radboud University
    • Radboud University, Institute for Molecules and Materials, 6525AJ Nijmegen, The Netherlands

  • Dmitry Smirnov

    • National High Magnetic Field Laboratory

  • Andrew Millis

    • Columbia University

  • Dmitri N Basov

    • Columbia University