Thermoelectric studies of Ir_1-xRh_xTe₂ (0 ≤ x ≤ 0.3)

We present the thermal transport properties of Ir_1-xRh_xTe₂ (0 ≤ x ≤ 0.3) alloy series where superconductivity emerges as the high-temperature structural transition (T_s) is suppressed. The isovalent Rh substitution in Ir_1-xRh_xTe₂ results in a slight reduction of lattice parameters and in an increase of number of carriers per unit cell. Positive thermopower S(T) values for all samples indicate the hole-type carriers. The decrease of S(T) in pure IrTe₂ (x = 0) at T_s implies that dimer formation is related to partial localization of hole-type carriers below the structural transition. Phonon-related thermal conductivity in pure IrTe₂ (x = 0) features a broad maximum around (50 – 60) K, which is significantly suppressed with Rh substitution. This is mostly contributed by the Rh/Ir doping disorder enhanced point defects scattering. Weak-coupled BCS superconductivity in Ir_0.8Rh_0.2Te₂ that emerges at low temperature (T_c^zero= 2.45 K) is most likely driven by electron-phonon coupling rather than dimer fluctuations mediated pairing.