Surface superconductivity in the Weyl semimetal MoTe2 detected by point contact spectroscopy

Naidyuk Y, Kvitnitskaya O, Bashlakov D, Aswartham S, Morozov I, Chernyavskii I, Fuchs G, Drechsler SL, Huehne R, Nielsch K, Buechner B, Efremov D (2018)

Publication Type: Journal article

Publication year: 2018

Journal

2D Materials IOP Science

Book Volume: 5

Article Number: 045014

Journal Issue: 4

DOI: 10.1088/2053-1583/aad3e2

Abstract

MoTe2 is a Weyl semimetal, which exhibits unique non-saturating magnetoresistance and strongly reinforced superconductivity under pressure. Here, we demonstrate that a novel mesoscopic superconductivity at ambient pressure arises on the surface of MoTe2 with a critical temperature up to 5 K significantly exceeding the bulk Tc = 0.1 K. We measured the derivatives of I-V curves for hetero-contacts of MoTe2 with Ag or Cu, homo-contacts of MoTe2 as well as 'soft' point contacts (PCs). Large number of these hetero-contacts exhibit a dV/dI dependence, which is characteristic for Andreev reflection. It allows us to determine the superconducting gap Δ. The average gap values are 2Δ = 1.30 ± 0.15 meV with a 2Δ/kBTc ratio of 3.7 ± 0.4, which slightly exceeds the standard BCS value of 3.52. Furthermore, the temperature dependence of the gap follows a BCS-like behavior, which points to a nodeless superconducting order parameter with some strong-coupling renormalization. Remarkably, the observation of a 'gapless-like' single minimum in the dV/dI of 'soft' PCs may indicate a topological superconducting state of the MoTe2 surface as these contacts probe mainly the interface and avoid additional pressure effect. Therefore, MoTe2 might be a suitable material to study new forms of topological superconductivity.

Involved external institutions

Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e.V. (IFW) / Leibniz Institute for Solid State and Materials Research Dresden

Germany (DE) National Academy of Sciences of Ukraine (NAN) / Національна академія наук України

Ukraine (UA)

How to cite

APA:

Naidyuk, Y., Kvitnitskaya, O., Bashlakov, D., Aswartham, S., Morozov, I., Chernyavskii, I.,... Efremov, D. (2018). Surface superconductivity in the Weyl semimetal MoTe2 detected by point contact spectroscopy. 2D Materials, 5(4). https://doi.org/10.1088/2053-1583/aad3e2

MLA:

Naidyuk, Yurii, et al. "Surface superconductivity in the Weyl semimetal MoTe2 detected by point contact spectroscopy." 2D Materials 5.4 (2018).

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