Distinct surface and bulk charge density waves in ultrathin 1T-TaS<sub>2</sub>
POSTER
Abstract
We employ variable temperature low-frequency Raman spectroscopy to study the nearly commensurate (NC) to commensurate (C) charge density wave (CDW) transition in 1T -TaS2 ultrathin flakes protected from oxidation. We identify additional modes originating from C-phase CDW phonons that are distinct from those seen in bulk 1T -TaS2. We attribute these to CDW modes from the surface layers. By monitoring individual modes with temperature, we find that surfaces undergo a separate, low-hysteresis NC-C phase transition that is decoupled from the transition in the bulk layers. This indicates the activation of a secondary phase nucleation process in the limit of weak interlayer interaction, which can be understood from energy considerations.
*Supported by NSF (CAREER Grant No. DMR-1552482, RUI Grant No. DMR-1410496, MRI Grant No. DMR-1337207, and NEB Grants No. 1124894), and the American Chemical Society Petroleum Research Fund (Grant No. 53401-UNI10).
Presenters
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Zhipeng Ye
- Texas Tech Univ