Single crystal growth and nano-structure study in a topological dirac metal, CoTe_2-δ

A single crystal of a topological material, CoTe_2-δ, has been grown via the chemical vapor transport method for a structural and electronic transport study. Single-crystal X-ray diffraction, powder X-ray diffraction, and high-resolution scanning electron microscope measurements confirm the high quality of the as-grown single crystals. In a high-resolution scanning electron microscopy study, a clear layered feature of the trigonal CoTe_2-δ crystal was observed. Fractal features and mosaic-type nanostructures were observed on the as-grown surface and cleaved surface, respectively. The trigonal CoTe_2-δ demonstrates a metallic ground state in transport measurements, with a typical carrier’s concentration in a 10²¹ cm⁻³ magnitude and a residual resistivity ratio of 1.6. Below 10 K, trigonal CoTe_2-δ contains quite complicated magnetoresistance behavior as a result of the competing effect between Dirac states and possible spin fluctuations.