Evidence of Nodal Superconductivity in Monolayer 1H‐TaS₂ with Hidden Order Fluctuations

Abstract

Unconventional superconductors represent one of the fundamental directions in modern quantum materials research. In particular, nodal superconductors are known to appear naturally in strongly correlated systems, including cuprate superconductors and heavy‐fermion systems. Van der Waals materials hosting superconducting states are well known, yet nodal monolayer van der Waals superconductors have remained elusive. Here, using low‐temperature scanning tunneling microscopy (STM) and spectroscopy (STS) experiments, we show that pristine monolayer 1H‐TaS2 realizes a nodal superconducting state. By including non‐magnetic disorder, we drive the nodal superconducting state to a conventional gapped s‐wave state. Furthermore, we observe the emergence of many‐body excitations close to the gap edge, signalling a potential unconventional pairing mechanism. Our results demonstrate the emergence of nodal superconductivity in a van der Waals monolayer, providing a building block for van der Waals heterostructures exploiting unconventional superconducting states.This article is protected by copyright. All rights reserved

Self-doped flat band and spin-triplet superconductivity in monolayer 1T-TaSe2−x Te x

“…We can see that the superconducting gap opens around the K highsymmetry points, but not along the Γ − M path [58]. This symmetry corresponds to a f y(y 2 −3x 2 ) nodal f-wave superconductor, which has been reported in TaS 2 for the 1H phase [59] and as a competing phase in NbSe 2 [60]. For Te concentrations of 1.225 ⩽ x ⩽ 1.231, the spin-triplet superconductor becomes gapped (figure 3(d)).…”

“…The symmetry in this case corresponds to a chiral p-wave p x + ip y spin-triplet phase (figure 3(f)). These nodal f-wave and the fully gapped p-wave phases could be experimentally distinguished based on the V or U-shaped gap in their spectra [59,61,62].…”

Stacking engineering in layered homostructures: transitioning from 2D to 3D architectures

“…For instance, monolayer 1T-TaS 2 is accepted as a Mott-insulator, 45–47 whereas monolayer 1H-TaS 2 is a superconductor. 48,49 Additionally, specific TMDs manifest topological electronic phases, such as the quantum spin hall effect in group-6 1T′-MX 2 . 50–54 These electronic phases in T-, T′- and H-phases, whether stable or metastable, are summarized in Fig.…”

Nature of the Unconventional Heavy-Fermion Kondo State in Monolayer CeSiI

“…This would have implications in the symmetry of the superconducting order parameters that might occur in the phase diagram of these heavy-fermion systems . The nodal behavior could be detected via ARPES experiments as previously done for the other Ce-based compounds or using a scanning tunneling microscope as it has already been used to test unconventional nodal superconductors. , …”