Highly Organized Epitaxy of Dirac Semimetallic PtTe₂ Crystals with Extrahigh Conductivity and Visible Surface Plasmons at Edges.

Abstract

Platinum telluride (PtTe₂), a member of metallic noble-transition-metal dichalcogenides (MNTMDs), has emerged as an indispensable candidate for superconducting, magnetic, and other electronic phase engineering, as well as optic applications. Herein, we report the van der Waals epitaxy of high-crystalline few-layer PtTe₂ crystals on inert mica. Density functional theory calculations are used to illustrate a type-II Dirac cone along the Γ-A direction in the PtTe₂ crystal. Impressively, the PtTe₂ devices exhibit an extra-high electrical conductivity of 10⁷ S m^-1, 1000 times higher than that of metallic 1T MoS₂. Meanwhile, the magnetoresistance effect at low temperatures reaches 800% in a field of 9.0 T. Furthermore, near-field nanooptical properties are assessed on PtTe₂. Considering the subwavelength effect, the plasmonic wavelength λ_p ≈ 200 nm of 1T PtTe₂ is obtained and the carrier concentration calculated from λ_p is about 1.22 × 10¹⁵ cm^-2, which is 100-fold higher than that of MoTe₂ in the previous reports. Therefore, our work demonstrates the growth of MNTMDs and provides insights into the plasmonic properties of 2D metallic telluride compounds.