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Observation of an Unconventional Anomalous Hall Effect in a New Ferromagnetic Weyl Semimetal CeAlSi

ORAL

Abstract

In the new ferromagnetic Weyl semimetal (FM WSM) CeAlSi, we find both a conventional and an unconventional anomalous Hall effect (AHE), that we name the loop Hall effect (LHE). The conventional AHE features a concurrent step increase in both Hall resistivity and magnetization when the applied field is along the magnetic easy-axis, similar to the AHE in the existing FM WSMs hosting finite Berry curvature. However, when the field is along the hard-axis, we observe the LHE, which does not exhibit a parallel field dependence between Hall resistivity and magnetization, in sharp contrast to the conventional AHE. More interestingly, by combining DFT calculation and quantum oscillation experiment, we find that the LHE only appears in the samples where the Fermi level lies within a short distance of 1 meV of the Weyl nodes. CeAlSi is also special in a way that both inversion and time-reversal symmetries are intrinsically broken which leads to a skewed distribution of Weyl nodes; this property may account for the unprecedentedly close connection between the LHE and Weyl nodes in CeAlSi.

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Presenters

  • Hung-Yu Yang

    Boston College

Authors

  • Hung-Yu Yang

    Boston College

  • Bahadur Singh

    Northeastern University, Physics, Northeastern University, SZU-NUS Collaborative Center, ShenZhen University, Department of Physics, Northeastern University

  • Jonathan Gaudet

    The Johns Hopkins University, Johns Hopkins University, Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University

  • Baozhu Lu

    Temple University, Temple Univ, Department of Physics, Temple University

  • Cheng-Yi Huang

    Academia Sinica, Physics and Astronomy, California State University, Northridge, Institute of Physics, Academia Sinica, Taipei, Taiwan

  • Wei-Chi Chiu

    Northeastern University

  • Shin-Ming Huang

    National Sun Yat-sen University, Natl Sun Yat Sen Univ, Physics, Natl Sun Yat Sen Univ, National Sun Yat-Sen University

  • Baokai Wang

    Northeastern University, Physics, Northeastern University

  • Faranak Bahrami

    Boston College

  • David E Graf

    Florida State University, National High Magnetic Field Laboratory, Florida State University, Department of Physics, National High Magnetic Field Laboratory, Florida State University, Florida, USA, National High Magnetic Field Laboratory, National High Magnetic Field Lab, Florida State University, National High Magnetic Field Laboratory and Department of Physics, Florida State University, Florida State Univ, Natl High Magnetic Field Lab, National High Magnetic Field Lab, Tallahassee, FL 32310, USA, National High Magnetic Field Laboratory, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310, USA, National High Magnetic Field Laboratory-Florida State University, National High Magnetic Field Laboratory, Tallahassee, FL, NHMFL, Florida State University, NHMFL

  • Guangyong Xu

    Center of Neutron Research, National Institute of Standards and Technology, Neutron-Condensed Matter Science Group, National Institute of Standards and Technology, National Institute of Standards and Technology, NIST, Center for Neutron Research, National Institute of Standards and Technology, NIST Center for Neutron Research, Oak Ridge National Laboratory

  • Hsin Lin

    Academia Sinica, Physics, Academia Sinica, Institute of Physics, Academia Sinica, Taipei, Taiwan, Institute of Physics, Academia Sinica

  • Darius Torchinsky

    Temple University, Temple Univ, Department of Physics, Temple University

  • Collin Leslie Broholm

    The Johns Hopkins University, Johns Hopkins University, Physics and Astronomy, Johns Hopkins University, Physics, The Johns Hopkins University, Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University

  • Arun Bansil

    Northeastern University, Physics, Northeastern University

  • Fazel Tafti

    Boston College