Thickness dependence of superconductivity in ultrathin NbS₂

Abstract

We report a systematic study of thickness-dependent superconductivity and carrier transport properties in exfoliated layered 2H-NbS2. Hall-effect measurements reveal 2H-NbS2 is a p-type metal with hole mobility of 1–3 cm2 V−1 s−1. The superconducting transition temperature is found to decrease with thickness. However, we find that superconductivity is suppressed due to disorder resulting from the incorporation of atmospheric oxygen. Cross-section transmission electron microscope imaging reveals a chemical change of NbS2 in the ambient, resulting in the formation of amorphous oxide layers sandwiching crystalline layered NbS2. Though few-nm-thick 2H-NbS2 completely converts to amorphous oxide in the ambient, PMMA encapsulation prevents further chemical change and preserves superconductivity in thicker samples.

Superconducting Quantum Metamaterials from High Pressure Melt Infiltration of Metals into Block Copolymer Double Gyroid Derived Ceramic Templates

“…[ 2–5 ] Extensive work has been performed on the effect of 2D confinement or ordering in the thin film regime, demonstrating, for example, the thickness dependence of transition temperature and tunable flux pinning in thin film periodic arrays. [ 6–10 ] In contrast, there have been far fewer investigations of 3D ordered superconductors and of the existing studies in this vein, all but a handful focus on isolated nano‐objects or nano‐wires. [ 11–13 ] The use of block copolymer (BCP) self‐assembly in the bulk gives access to numerous 3D co‐continuous network morphologies (including chiral networks), and may impart the ability to control structure across characteristic lengths in superconductors (i.e., London penetration depth, Ginzburg–Landau correlation length).…”

Magnetic structure investigation of the intercalated transition metal dichalcogenide V1/3NbS2

“…Our data are consistent with the presence of the k 0 magnetic reflections; however, there is another set of reflections which cannot be accounted for using just this propagation vector. Indexing of these reflections requires a second propagation vector k 1 = (0, 0, 1 3 ). With the current data we cannot unambiguously confirm whether these two propagation vectors belong to the same or different phases.…”

“…Magnetic moments on the vanadium atoms in a unit cell of V 1/3 NbS 2 viewed along the a * direction. (a) In-plane moments associated with the k 0 = (0, 0, 0) propagation vector, (b) the out-of-plane up-down-down moments associated with the k 1 = (0, 0, 1 3 ) propagation vector, and (c) the superposition of these two components.…”

“…The transition metal dichalcogenides (TMDCs) are a family of materials that have attracted considerable interest over the years due to the properties they exhibit such as superconductivity [1][2][3], charge density waves [4,5], and even defect-induced magnetism in Mo-based TMDCs [6,7]. The subset of this family that adopts the hexagonal 2H-X S 2 polytype, where X is a transition metal, crystallizes in structures formed of layers bound together by the weak van der Waals force, allowing thin layers (monolayers, bilayers, etc.)…”

“…We have used techniques such as powder and single-crystal neutron diffraction, as well as heat capacity and magnetization measurements, to probe the magnetic structure of V 1/3 NbS 2 . We show that V 1/3 NbS 2 becomes antiferromagnetic below 50 K. Two magnetic propagation vectors have been extracted from the powder neutron diffraction data: k 0 = (0, 0, 0) and k 1 = (0, 0, 1 3 ). The k 0 propagation vector represents an in-plane component of the magnetism, with antiferromagnetically coupled ferromagnetic layers of vanadium atoms.…”