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

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=0.1K. We measured the derivatives of I-V curves for metallic 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 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.

arXiv comment9 pages, 7 figures. Presented at the 6th International Conference on Superconductivity and Magnetism (ICSM2018), April 29 - May 04, 2018 (Antalya, Turkey); V2: Discussion extended, seven Refs. added, accepted to "2D Materials" journal

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Cited by in corpus (18)

• Ab initio approach to the elastic, electronic, and optical properties of MoTe2: A topological Weyl semimetal
• Evidence for Helical Hinge Zero Modes in an Fe-Based Superconductor
• Strain-sensitive superconductivity in kagome metals KV${}_3$Sb${}_5$ and CsV${}_3$Sb${}_5$ probed by point-contact spectroscopy
• Surface superconductivity in the topological Weyl semimetal t-PtBi${}_2$
• Experimental search for the origin of low-energy modes in topological materials
• Electron-phonon interaction and point contact enhanced superconductivity in trigonal PtBi2
• Superconducting properties of MoTe${}_2$ from the $abinitio$ anisotropic Migdal-Eliashberg theory
• Layered van der Waals topological metals of TaTMTe4 (TM = Ir, Rh, Ru) family
• Topological phase transition in MoTe${}_2$: A Review
• Superconductivity in doped Weyl semimetal Mo${}_{0.9}$Ir${}_{0.1}$Te${}_2$ with broken inversion symmetry
• Equilibrium current in a Weyl-semimetal - superconductor heterostructure
• Resolving different pairing states in Weyl superconductors through the single-particle spectrum
• Phonon-mediated intrinsic topological superconductivity in Fermi arcs
• Yanson point-contact spectroscopy of Weyl semimetal WTe2
• Switchable domains in point contacts based on transition metal tellurides
• Peculiarities of electron transport and resistive switching in point contacts on TiSe2, TiSeS and CuxTiSe2
• Enhanced critical temperatures in the strongly overdoped iron-based superconductors AFe${}_2$As${}_2$ (A = K, Cs, Rb) observed by point contacts
• Electron-phonon interaction, magnetic phase transition, charge density waves and resistive switching in VS2 and VSe2 revealed by Yanson point contact spectroscopy