Physical properties of polycrystalline Dy2PdGe6 and La2PdGe6

Abstract

Polycrystalline samples of the intermetallic compounds Dy2PdGe6 and La2PdGe6 which crystallize in the orthorhombic structure (Cmca space group) were studied by means of magnetic, electrical resistivity, specific heat and differential thermoelectric power measurements. The Dy-germanide is an antiferromagnet below 25(1)K and at low temperature and above magnetic fields of 3.5T it exhibits a metamagnetic behaviour. Especially the specific heat measurements point to well-localized 4f-electrons in this compound. Whereas the isostructural La-germanide is a nonmagnetic material taken here as a reference compound. A good overall fit of the resistivity to a general Bloch–Grüneisen formula indicates its metallic character in contrast to the Dy-germanide being a semimetallic-like conductor. For the latter compound in its ordered state the electrical resistvity, specific heat and thermoelectric power are dominated by electron–magnon scattering with antiferromagnetic spin-wave spectrum typical of anisotropic antiferromagnetic systems. The observed Schottky anomaly yields an assumed crystal field scheme of low-energy lying levels. Its thermoelectric power behaviour achieves medium positive values at high temperatures, indicating a hole domination in electrical transport properties. On the other hand, S(T) below TN for Dy- and in the whole temperatures measured for La-based compounds is negative, pointing to their electron carrier origin.