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Abstract NaCl has widely been used as a seeding promoter for chemical vapor deposition of large-scale 2D transition metal dichalcogenides. In this work, we report a study of the influence of NaCl on the growth and optical properties of layered CVD-grown WS2using steady-state and time-resolved Kerr rotation measurements at room temperature. Strong photoluminescence (PL) signals from single flakes grown with a low NaCl content indicates direct band-gap emission, whereas flakes grown with higher amounts of NaCl exhibit red-shifted, weaker PL. Raman measurements from single flakes also indicate that WS2grown with higher NaCl amounts result in multilayered structures, while lower NaCl quantities yield monolayer WS2. Ultrafast carrier decay measurements from single flakes also indicate a NaCl-dependent on the valley exchange interaction component (<10 ps) and slower decay components (>50 ps), attributed to a combination of phenomena, such as the band gap transitioning from direct to indirect and defect-related localized states. Our study provides insight into the influence of seeding promoters in layered CVD-grown WS2in particular and 2D transition metal dichalcogenides in general.
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Nitrogen‐Vacancy Magnetometry of Edge Magnetism in WS 2 Flakes
Abstract Two‐dimentional magnets are of significant interest both as a platform for exploring novel fundamental physics and for their potential in spintronic and optoelectronic devices. Recent bulk magnetometry studies have indicated a weak ferromagnetic response in tungsten disulfide (WS2), and theoretical predictions suggest edge‐localized magnetization in flakes with partial hydrogenation. Here, room‐temperature wide‐field quantum diamond magnetometry to image pristine and Fe‐implanted WS2flakes of varying thicknesses (45–160 nm), exfoliated from bulk crystals and transferred to NV‐doped diamond substrates, is used. Direct evidence of edge‐localized stray magnetic fields, which scale linearly with applied external magnetic field (4.4–220 mT), reaching up to ±4.7 µT, is observed. The edge signal shows a limited dependence on the flake thickness, consistent with dipolar field decay and sensing geometry. Magnetic simulations using five alternative models favor the presence of edge magnetization aligned along an axis slightly tilted from the normal to the WS2flake's plane, consistent with spin canting in antiferromagnetically coupled edge states. Thses findings establish WS2as a promising platform for edge‐controlled 2D spintronics.
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- PAR ID:
- 10613982
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 35
- Issue:
- 38
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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