Large Metallic Vanadium Disulfide Ultrathin Flakes for Spintronic Circuits and Quantum Computing Devices

Abstract

Atmospheric pressure chemical vapor deposition (APCVD) is employed for the synthesis of layered vanadium disulfide. By tuning several critical growth parameters, we achieve VS 2 flakes with lateral dimension over 100 μm and thickness down to monolayer (∼0.59 nm) and bilayer (∼1.17 nm), which are larger and thinner than those previously reported in the literature. Furthermore, ultrathin flakes with thicknesses of several atomic layers are directly synthesized on mica and SiO 2 substrates without the use of an exfoliation method. X-ray diffraction and high-resolution transmission electron microscopy confirm the flakes' monocrystalline quality. Raman spectra are collected and are consistent with the vibrational modes for the trigonal phase of VS 2 as determined by density functional theory calculations. Through electron backscatter diffraction pole figure analysis, transmission electron microscopy, and optical microscopy, a complex epitaxial relationship with nine preferred in-plane orientations is observed in some regions of the VS 2 /mica samples. Remarkably, this is in agreement qualitatively with a superlattice area mismatch model, providing further evidence of the interfacial interactions with mica dictating the nucleation of film atoms in van der Waals heterostructures. Finally, magnetic force microscopy measurements suggest room-temperature ferromagnetism in ultrathin VS 2 flakes, in agreement with several density functional theory calculations. The discovery of an ultrathin ferromagnetic metal such as VS 2 may have an impact on emerging fields such as spintronics and quantum computing.

Out-of-Plane Deformations Determined Mechanics of Vanadium Disulfide (VS2) Sheets

“…We can clearly identify two main diffraction peaks corresponding to (001) and (011) from VS 2 crystals as shown in Figure c, which agrees with the one reported in the literature of VS 2 nanosheets synthesized by using the CVD method. , Specifically, the (001) peak at 2θ = 15.52° corresponds to a d -spacing of ∼5.703 Å. This is within 1.0% of the theoretical d (001)-spacing of 5.755 Å, , indicating that the possible presence of interstitial V atoms within the van der Waals gap introduced negligible distortion in the 1T-phase atomic structure of VS 2 Figure d presents the Raman spectrum of VS 2 nanosheets prepared on SiO 2 /Si substrate.…”

Recent Advances in 2D Group VB Transition Metal Chalcogenides

“…[ 21,22 ] Also, the 2D GVTMCs become extremely sensitive to the surrounding stimulations, such as light, [ 127 ] gases, [ 39 ] biomolecules, [ 37 ] and chemical agents, [ 38 ] thus enabling the development of a variety of sensors with high specificity. Noteworthily, the ferromagnetism in 2D VS 2 , [ 23,152 ] VSe 2 , [ 24–27,69 ] and Ta 3 FeS 6 [ 46,102 ] has been demonstrated, making GVTMCs as the particularly attractive 2D magnetic materials for van der Waals spintronic applications.…”

Probing Ferrimagnetic Semiconductor with Enhanced Negative Magnetoresistance: 2D Chromium Sulfide

“…f) Summary of the figure of merit and roadmap of 2D magnetoresistive devices (detailed data are tabulated in Table S6, Supporting Information); the number denotes the references of earlier reported 2D materials. [ 1,19,37–48 ]…”