Two-Dimensional 2M-WS₂ Nanolayers for Superconductivity

Abstract

Recently, a newly discovered VIB group transition metal dichalcogenide (TMD) material, 2M-WS2, has attracted extensive attention due to its interesting physical properties such as topological superconductivity, nodeless superconductivity, and anisotropic Majorana bound states. However, the techniques to grow high-quality 2M-WS2 bulk crystals and the study of their physical properties at the nanometer scale are still limited. In this work, we report a new route to grow high-quality 2M-WS2 single crystals and the observation of superconductivity in its thin layers. The crystal structure of the as-grown 2M-WS2 crystals was determined by X-ray diffraction (XRD) and scanning tunneling microscopy (STM). The chemical composition of the 2M-WS2 crystals was determined by energy dispersive X-ray spectroscopy (EDS) analysis. At 77 K, we observed the spatial variation of the local tunneling conductance (dI/dV) of the 2M-WS2 thin flakes by scanning tunneling spectroscopy (STS). Our low temperature transport measurements demonstrate clear signatures of superconductivity of a 25 nm-thick 2M-WS2 flake with a critical temperature (T C) of ∼8.5 K and an upper critical field of ∼2.5 T at T = 1.5 K. Our work may pave new opportunities in studying the topological superconductivity at the atomic scale in simple 2D TMD materials.

Inducing chiral superconductivity on honeycomb lattice systems

“…Superconducting states at low electron doping are observed below 1 K in WTe 2 monolayers [37]. Similarly, superconductivity in high-quality 2M-WS 2 single crystals has been reported by several groups experimentally [38,39]. This unsual material is predicted to exhibit topological nodeless superconductivity, with probable Majorana states bound to vortex cores.…”

Nonvolatile Memristive Effect in Few-Layer CrI3 Driven by Electrostatic Gating

“…The few-layer CrI 3 -based tunnel junction devices were fabricated by directly transferring the prepared CrI 3 thin layers (Figure S1) on top of predefined Pt electrodes on Si/SiO 2 (280 nm) substrates using the dry transfer method − (see Methods in Supporting Information). Figure a shows a schematic side view of a bilayer-CrI 3 tunnel junction device with both top (graphite) and bottom (heavily doped Si) gates.…”

Atomic-Resolution Imaging of Micron-Sized Samples Realized by High Magnetic Field Scanning Tunneling Microscopy

“…Traditional STMs are capable of working at room temperature [ 2 , 3 ], in liquid [ 4 , 5 ], at low temperature [ 6 , 7 ], and in ultra-high vacuum conditions [ 8 , 9 ] in order to investigate different physical and chemical properties. With the rapid development of material science, small-sized samples in micron dimension are widely synthesized and studied [ 10 , 11 , 12 ]. As is known, graphene has attracted a significant amount of interest from researchers [ 13 , 14 ].…”