Magnetism in REPdSn ( RE = La, Pr, Nd) compounds: A single-crystal study

Abstract

The lack of data obtained on single crystals of the REPdSn intermetallic compounds ( RE = La, Pr, Nd) motivated us to grow single crystals of these compounds and to study intrinsic magnetic and related electronic and thermal properties of these materials with an emphasis on magnetocrystalline anisotropy. All the three compounds crystallize in the orthorhombic TiNiSi-type crystal structure. The results of specific heat, magnetization and resistivity measurements have revealed that LaPdSn is a paramagnet at temperatures down to 2 K, PrPdSn and NdPdSn order antiferromagnetically below T N = 4.2(1) and 3.4(1) K, respectively, and exhibit considerable magnetocrystalline anisotropy. The latter compound undergoes an order-to-order phase transition at 1.9(3) K. At sufficiently high temperatures the susceptibility of the Pr- and Nd-compounds follows a Curie–Weiss law with the effective magnetic moment almost identical in all the three principal crystallographic directions to the value expected for the corresponding free RE 3+ ion. The values of the paramagnetic Curie temperature manifest the anisotropy of the susceptibility in paramagnetic state, which is particularly pronounced for PrPdSn. As temperature decreases the susceptibility exhibits anisotropic departure from the Curie–Weiss behavior as a consequence of the crystal field (CF) influence on the RE ions. The involvement of the crystal field in the magnetism of the RE ions is also reflected in the Schottky contribution to the specific heat which reflects the splitting of the CF energy levels and the reduced values of the RE ordered magnetic moments due to the unpopulated higher-energy CF energy levels at low temperatures. Interesting features of magnetism in PrPdSn and NdPdSn are reflected also in the electrical resistivity and magnetoresistivity. For closer understanding of magnetism in the studied REPdSn compounds we have also performed first principles electronic structure calculations. We present the calculated density of states (DOS) of REPdSn compounds and we also compare the obtained experimental results with the theoretical predictions from the calculated electronic structure.