Point-contact spectroscopic study of Weyl semimetals MoTe<sub>2</sub> and WTe<sub>2 </sub>

ORAL

Abstract

The Andreev-reflection (AR) double-minimum structure was observed in dV/dI curves of “hard” MoTe2/Ag point contacts (PCs) with enhanced. Tc up to 5 K. The extracted superconducting (SC) gap Δ has a BCS-like dependence with 2Δ/kBTc =3.7+/-0.4 averaged over 9 PCs. Remarkably, the observation of a single zero-bias minimum in dV/dI of “soft” PCs (i.e. using silver paint instead of Ag wire) may indicate a topological “gapless-like” SC state of the MoTe2 surface, since “soft” contacts probe mainly the interface and avoid pressure effect. The Yanson point-contact (PC) electron-phonon interaction (EPI) spectra of MoTe2 demonstrate only a broad maximum around 18 meV. Contrary, dV/dI curves of WTe2 PCs show tiny SC features if at all, but display an EPI structure with maxima at 8 and 16 meV. Thus, Yanson PC spectra demonstrate the presence of solely phononic excitations for both MoTe2 and WTe2, while AR spectra show a “gapless-like” SC state only in MoTe2 (at least above 2.5K). Interestingly. For both compounds a broad maximum in dV/dI at large voltages (>100mV) was observed indicating some phase transition. The latter might be induced by the high current density in the PC and/or local heating, thus enabling the manipulation of the quantum electronic states at the interface in the PC core.

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Presenters

  • Yurii Naidyuk

    • B.Verkin Institute for Low Temperature Physics and Engineering, NASU, Kharkiv, Ukraine

Authors

  • Yurii Naidyuk

    • B.Verkin Institute for Low Temperature Physics and Engineering, NASU, Kharkiv, Ukraine

  • Dima L. Bashlakov

    • B.Verkin Institute for Low Temperature Physics and Engineering, NASU, Kharkiv, Ukraine

  • Oksana E. Kvitnitskaya

    • B.Verkin Institute for Low Temperature Physics and Engineering, NASU, Kharkiv, Ukraine

  • Saicharan Aswartham

    • Leibniz Institute for Solid State and Materials Research

  • Igor V. Morozov

    • Lomonosov Moscow State University

  • Ivan Chernyavskii

    • Lomonosov Moscow State University

  • Grigory Shipunov

    • Leibniz Institute for Solid State and Materials Research

  • Günter Fuchs

    • Leibniz Institute for Solid State and Materials Research

  • Stefan-Lüdwig Drechsler

    • Institute for Theoretical Solid State Physics, IFW Dresden
    • Leibniz Institute for Solid State and Materials Research

  • Dr.Ruben Hühne

    • Leibniz Institute of Solid State and Materials Research (IFW Dresden), Helmholtzstr. 20, 01069 Dresden, Germany
    • Leibniz Institute for Solid State and Materials Research

  • Kornelius Nielsch

    • Institute of Metallic Materials, Leibniz IFW - Dresden
    • Leibniz IFW and TU Dresden
    • Leibniz Institute of Solid State and Materials Research (IFW Dresden), Helmholtzstr. 20, 01069 Dresden, Germany
    • Leibniz Institute of Solid State and Materials Research (IFW Dresden), Helmholtzstr. 20, 01069 Dresden, Germany; Institute of Applied Physics, Technische Universität Dresden,
    • Leibniz Institute for Solid State and Materials Research
    • Leibniz Institute of Solid State and Materials Research (IFW Dresden), Helmholtzstr. 20, 01069 Dresden, Germany; Institute of Materials Science, Technische Universität Dresde

  • Bernd Büchner

    • Institute for Solid State Physics, IFW Dresden
    • Leibniz Institute for Solid State and Materials Research
    • Leibniz-Institut für Festkörper- und Werkstoffforschung (IFW) Dresden, 01171 Dresden, Germany

  • Dmitri Efremov

    • IFW - Dresden
    • Leibniz Institute for Solid State and Materials Research