Magnetic and transport properties of half-Heuslers, RPdSb (RÂ =Â Gd and Tb)

We present the results of our studies on rare-earth half-Heuslers, RPdSb (R = Gd and Tb), crystallizing in a LiGaGe-type hexagonal structure, by means of magnetization, heat capacity, electrical resistivity, Seebeck coefficient, thermal conductivity and magnetoresistance measurements. The compounds exhibit antiferromagnetic order with transition temperatures of 17 and 2.5 K for Gd and Tb samples, respectively. The results of electrical transport measurements establish a metallic behavior for both the samples while the deviation from the linear temperature dependence was explained based on the additional contribution from the s-d inter-band scattering. Moreover, thermal transport measurements also indicate the contribution due to the s-d interaction where both the types of charge carriers involved in scattering. The positive sign of Seebeck coefficient confirms the dominant charge carriers as holes with the carrier concentration of ∼1021 cm−3 at room temperature while the magnitude decreases with temperature non-linearly. The most interesting feature is the observation of giant positive and non-saturating magneto-resistance at low temperatures which is essentially linear at higher fields and resembles the behavior of charge compensated materials. These results were explained on the basis of the temperature dependent changes in the population of electrons and holes.