Layered van der Waals topological metals of TaTMTe4 (TM = Ir, Rh, Ru) family

Abstract

Layered van der Waals materials of the family TaTMTe4 (TM=Ir, Rh, Ru) are showing very interesting electronic properties. Here we report the synthesis, crystal growth and structural characterization of TaIrTe4, TaRhTe4, TaIr1-x Rhx Te4 (x = 0.06; 0.14; 0.78; 0.92) and Ta1+x Ru1-x Te4 single crystals. For Ta1+x Ru1-x Te4 off-stoichiometry is shown. X-ray powder diffraction confirms that TaRhTe4 is isostructural to TaIrTe4. We show that all these compounds are metallic with diamagnetic behavior. Ta1.26(2)Ru0.75(2)Te4.000(8) exhibits an upturn in the resistivity at low temperatures which is strongly field dependent. Below T ≈ 4K we observed signatures of the superconductivity in the TaIr1-x Rhx Te4 compounds for x = 0.92. Magnetotransport measurements on all samples show weak magnetoresistance (MR) field dependence that is typically quadratic-in-field. However, for TaIr1-x Rhx Te4 with x ≈ 0.78, the MR has a linear term dominating in low fields that indicates the presence of Dirac cones in the vicinity of the Fermi energy. For TaRhTe4 series the MR is almost isotropic. We have performed electronic structure calculations for isostructural TaIrTe4 and TaRhTe4 together with the projected total density of states. The main difference is appearance of the Rh-band close to the Fermi level.