Temperature-dependent Raman spectroscopy in double spiral WS₂ nanostructures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Complex morphological hierarchies in 2D transition metal dichalcogenides (TMDs) are crucial for advanced applications.
• The thermal properties of multi-spiral TMD architectures remain largely unexplored due to complex strain and interlayer interactions.

Purpose of the Study:

• To investigate the temperature-dependent thermal properties of double-spiral WS2.
• To understand the influence of morphology on thermal behavior and phonon interactions.

Main Methods:

• Temperature-dependent Raman spectroscopy from 150-450 K.
• Multi-peak Lorentzian fitting to extract optical modes (E12g and A1g).
• Analysis using thermal expansion and multiphonon models.

Main Results:

• Double-spiral WS2 shows a weaker temperature response compared to monolayer and single-spiral structures.
• Distinct temperature-dependent Raman shift behaviors were observed between layers in different spirals.
• Thermal expansion is the primary driver of nonlinear temperature dependence, with the three-phonon process dominating shift magnitude.

Conclusions:

• The study elucidates the thermal behavior of double-spiral WS2, highlighting the impact of morphology.
• Findings suggest thermal expansion and phonon interactions govern the observed temperature dependence.
• Potential evidence for negative thermal expansion in WS2 warrants further investigation.