Quantum transport evidence of Weyl fermions in an epitaxial ferromagnetic oxide SrRuO<sub>3</sub> thin film

ORAL

Abstract

SrRuO3, a 4d ferromagnetic perovskite, provides a promising opportunity to seek the existence of Weyl fermions in magnetic materials. However, such a quest has been hampered until our latest report [1] due to difficulties in preparing high-quality specimens [2]. Here, we demonstrate the quantum transport evidence of the Weyl fermions in an epitaxial SrRuO3 film with the best crystalline quality ever reported. We grew 63-nm thick SrRuO3 films on SrTiO3 substrates by our recently developed machine-learning-assisted molecular beam epitaxy [3]. The residual resistivity ratio [ρ(300 K)/ρ(T→0 K)] of the film reached the world’s best value of 84, enabling direct observations of quantum transport evidence of Weyl fermions [1,4]: (i) unsaturated linear positive magnetoresistance (MR), (ii) chiral-anomaly-induced negative MR, (iii) π Berry phase accumulated along cyclotron orbits, (iv) light cyclotron masses, and (v) high quantum mobility of about 10000 cm2/Vs. Therefore, our results establish SrRuO3 as a magnetic Weyl semimetal.

[1] K. Takiguchi, Y. K. Wakabayashi, et al., Nat. Commun. 11, 4969 (2020).
[2] G. Koster, et al., Rev. Mod. Phys. 84, 253 (2012).
[3] Y. K. Wakabayashi, et al., APL Mater. 7, 101114 (2019).
[4] X. Huang, et al., Phys. Rev. X 5 031023 (2015).

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Presenters

  • Kosuke Takiguchi

    • NTT Basic Research Laboratories
    • Univ of Tokyo

Authors

  • Kosuke Takiguchi

    • NTT Basic Research Laboratories
    • Univ of Tokyo

  • Yuki Wakabayashi

    • NTT Basic Research Labs
    • NTT Basic Research Laboratories

  • Hiroshi Irie

    • NTT Basic Research Labs
    • NTT Basic Research Laboratories

  • Yoshiharu Krockenberger

    • NTT Basic Research Labs
    • NTT Basic Research Laboratories

  • Takuma Otsuka

    • NTT Communication Science Laboratories

  • Hiroshi Sawada

    • NTT Basic Research Labs
    • NTT Communication Science Laboratories

  • Sergey A Nikolaev

    • Laboratory for Materials and Structures, Tokyo Institute of Technology

  • Hena Das

    • Laboratory for Materials and Structures, Tokyo Tech World Research Hub Initiative, Institute of Innovative Research, Tokyo Inst of Tech - Yokohama
    • Laboratory for Materials and Structures, Tokyo Institute of Technology

  • Masaaki Tanaka

    • Department of Electrical Engineering and Information Systems, The University of Tokyo
    • Electrical Engineering and Information System, Univ of Tokyo
    • Electrical Engineering and Information Systems, Univ of Tokyo
    • Univ of Tokyo

  • yoshitaka taniyasu

    • NTT Basic Research Labs
    • NTT Basic Research Laboratories

  • Hideki Yamamoto

    • NTT Basic Research Labs
    • NTT Basic Research Laboratories