Experimental Evidence of Stable 2H Phase on the Surface of Layered 1$T'$-TaTe₂

We report on the low-energy electronic structure of Tantalum ditelluride (1$T'$-TaTe₂), one of the charge density wave (CDW) materials from the group V transition metal dichalcogenides using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT). We find that the Fermi surface topology of TaTe₂ is quite complicated compared to its isovalent compounds such as TaS₂, TaSe₂, and isostructural compound NbTe₂. More importantly, we discover that the surface electronic structure of 1$T'$-TaTe₂ has more resemblance to the 2H-TaTe₂, while the bulk electronic structure has more resemblance to the hypothetical 1T-TaTe₂. These experimental observations are thoroughly compared with our DFT calculations performed on 1T-, 2H- and 2H (monolayer)/1T- TaTe₂. We further notice that the Fermi surface topology is temperature independent up to 180 K, confirming that the 2H phase on the surface is stable up to 180 K and the CDW order is not due to the Fermi surface nesting.