Structure and transport properties of the quasi-one-dimensional telluride Ta1.2Os0.8Te4

Abstract

We report the crystal growth, structural characterization, and physical properties of an off-stoichiometric van der Waals telluride ${\mathrm{Ta}}_{1.2}{\mathrm{Os}}_{0.8}{\mathrm{Te}}_{4}$, which is isostructural with the noncentrosymmetric ${\mathrm{WTe}}_{2}$, a prototypical type-II Weyl semimetal. Transport measurements have been carried out in magnetic fields up to 9 T. A low-temperature resistivity upturn is observed along all three crystallographic directions at zero field. The along-chain ${\ensuremath{\rho}}_{a}$ and interchain ${\ensuremath{\rho}}_{b}$ are found to increase logarithmically at low temperatures, while in the low-$T$ metallic regime, both longitudinal and transverse transports support a three-dimensional Fermi liquid ground state. As temperature is further increased, successive crossovers to electronic states of reduced dimensionality can be seen in both interchain resistivities. The transverse magnetoresistance is weak but anisotropic, the analysis of which indicates the Kohler's rule is severely violated over a large temperature range. The positive linear field dependence of Hall resistivity at selected temperatures indicates the dominance of single-band hole-type charge carriers, consistent with the results of the angle-resolved photoemission spectroscopy. Our results not only establish this transition-metal telluride family as a good system for studying various dimensional crossover phenomena, but also offer the potential for exploring topologically nontrivial phases with reduced dimensionality, given its structural similarity to ${\mathrm{WTe}}_{2}$.