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 interesting electronic properties. We report the growth and characterization of TaIrTe₄, TaRhTe₄, TaIr_1-<i>x</i>Rh_<i>x</i>Te₄ (<i>x</i> = 0.06, 0.14, 0.78, 0.92), Ta_1+<i>x</i>Ru_1-<i>x</i>Te₄ single crystals. X-ray powder diffraction confirms that TaRhTe₄ is isostructural to TaIrTe₄. All these compounds are metallic with diamagnetic behavior. Below <i>T</i> ≈ 4 K we observed signatures of the superconductivity in the TaIr_1-<i>x</i>Rh_<i>x</i>Te₄ compounds for <i>x</i> = 0.92. All samples show weak quadratic-in-field magnetoresistance (MR). However, for TaIr_1-<i>x</i>Rh_<i>x</i>Te₄ with <i>x</i> ≈ 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. Electronic structure calculations for TaIrTe₄ and TaRhTe₄ reveal appearance of the Rh band close to the Fermi level.