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

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APS March Meeting 2019

Volume 64, Number 2

Monday–Friday, March 4–8, 2019; Boston, Massachusetts

Session E05: Topological Superconductivity: TMD, Quantum Wells

8:00 AM–11:00 AM, Tuesday, March 5, 2019
BCEC Room: 108

Sponsoring Unit: DMP
Chair: Vidya Madhavan, Univ of Illinois - Urbana

Abstract: E05.00002 : Point-contact spectroscopic study of Weyl semimetals MoTe₂ and WTe₂

8:36 AM–8:48 AM

Abstract

Presenter:

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
(Leibniz Institute for Solid State and Materials Research)

Dr.Ruben Hühne
(Leibniz Institute for Solid State and Materials Research)

Kornelius Nielsch
(Leibniz Institute for Solid State and Materials Research)

Bernd Büchner
(Leibniz Institute for Solid State and Materials Research)

Dmitri Efremov
(Leibniz Institute for Solid State and Materials Research)

The Andreev-reflection (AR) double-minimum structure was observed in dV/dI curves of “hard” MoTe₂/Ag point contacts (PCs) with enhanced. T_cup to 5 K. The extracted superconducting (SC) gap Δ has a BCS-like dependence with 2Δ/k_BT_c =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 MoTe₂demonstrate 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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Bulletin of the American Physical Society

APS March Meeting 2019

Volume 64, Number 2

Monday–Friday, March 4–8, 2019; Boston, Massachusetts

Session E05: Topological Superconductivity: TMD, Quantum Wells

Abstract: E05.00002 : Point-contact spectroscopic study of Weyl semimetals MoTe2 and WTe2

Presenter:

Authors:

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Abstract: E05.00002 : Point-contact spectroscopic study of Weyl semimetals MoTe₂ and WTe₂