Electrical properties of Te-rich TaTe_xSe_2-x single crystals

Tantalum-based transition metal dichalcogenides exhibit a range of emergent structural and electronic properties, including superconductivity and charge density waves, that are highly sensitive to composition. While TaSe₂ has been widely investigated, the tellurium-rich region of the TaTe_xSe_2-x system remains largely unexplored. In this work, polycrystalline and single-crystalline TaTe_xSe_2-x (1.4 ≤ x ≤ 1.9) were synthesized using solid-state and chemical vapor transport methods to investigate the relation of crystal structure and electrical transport with increasing Te-content. Powder X-ray diffraction reveals a structural transition from the trigonal 1T phase to the distorted 1T' phase toward the Te-rich limit, accompanied by drastic changes in lattice parameters. Scanning electron microscopy and energy dispersive X-ray spectroscopy confirm homogenous composition and high crystallinity of the grown single crystals. Electronic structure calculations indicate metallic character across the compositional range with only minor changes near the Fermi level upon Te substitution. Electrical resistivity measurements demonstrate composition-dependent metallic transport governed by disorder-dominated scattering and electron-electron interactions at low temperatures and high Te-content. Magnetoresistance measurements further support a disorder-driven transport regime in a multiband system, consistent with the presence of both electron and hole pockets. These results provide insights into the structure-property relationships in Te-rich TaTe_xSe_2-x and clarify the compositional dependence of transport behaviour approaching TaTe₂.