The magnetic and electronic properties of REAgSb2 compounds

Abstract

Magnetic properties and electronic structure of REAgSb2 compounds (RE = La-Nd, Sm and Gd-Er) were investigated by experimental measurements on their polycrystalline samples combining with first-principles calculation. X-ray powder diffraction analysis shows that all compounds crystallize in a tetragonal HfCuSi2-type structure (Space group P4/nmm, No. 129, tP8). The results of magnetic measurements reveal that LaAgSb2 is non-magnetic, CeAgSb2 is ferromagnetic, and other compounds are antiferromagnetic. The magnetic ordering temperatures were obtained by dM/dT plots, which are distributed between 3.2 and 14.2 K. According to Curie-Weiss law, it was found that the effective magnetic moments of these compounds are close to rare earth trivalent ions in REAgSb2. The metamagnetic transitions are observed for REAgSb2 (RE = Pr, Gd-Ho) according to M−H curves at 2 K. The Arrott plots reveal that the magnetic phase transition type belongs to second-order phase transition for REAgSb2 (RE = Ce, Pr). The maximum magnetic entropy changes of CeAgSb2 and PrAgSb2 are measured to be 5.1 and 7.9 J.kg−1.K−1, respectively. The electronic structures of REAgSb2 compounds have been studied based on density functional theory. The electronic structures data of REAgSb2 suggest that the DOS dispersions are close to the RE 4f electrons and there is a strong correlation between RE and Sb atoms. The hybridization between RE 4f and Sb 5p electrons gradually increases as a function of atomic number for REAgSb2 (RE = Ce-Sm, Gd), while gradually decreases for the other compounds.