Thermodynamic and electrical properties of GdNiIn compound

Abstract

Rareearth based ternary intermetallic compounds (R-TX), with R=rare earth, T=transition metal and X=pelectron element, are interesting systems from the technological and basic research point of views. Rare-earth based ternaries are found to be promising alternatives as a hydrogen-storage method offering safety advantages over other types of hydrogen storage. They are attractive candidates due to their high hydrogen capacity per volume unit and their ability to absorb hydrogen under moderate conditions. On the other hand, R-Ni-In compounds which crystallize in the ZrNiAl-type hexagonal crystal structure, show interesting crystallographic features. R atoms occupy positions that form a triangular structure in a similar way as a Kagom´ e lattice does. That triangular coordination symmetry of R atoms can provide the ideal scenery for a geometrical frustration of magnetic interactions. In this work, the study of the structural, electrical and thermodynamic properties of GdNiIn is presented. Polycrystalline sample of GdNiIn were prepared from high pure elements by arc melting in argon atmosphere. The sample was annealed in vacuum at 800oC for 48h to warrant the phase formation and homogeneous sample. Crystal-structure characterization and phase determination were carried out by X-ray diffraction (XRD). Magnetization (M) measurements were carried out using a commercial PPMS system in a broad range of temperature (2-300K) and magnetic f ields up to 9T. DC resistivity (ρ) measurements were performed using the four-point probe method. XRD data analysis indicates the formation of the hexagonal structure with lattice constants a=0.7489(1) nm and c=0.3835(2) nm. M vs. T curve suggests a ferromagnetic order with a TC = 86K. M vs. H curve obtained at 5K indicates that this compound shows an anhysteretic behavior and provides a saturation moment of 7.6µB. This value is in agreement with the effective magnetic moment (µeff = 8.2µB) obtained from the Curie-Weiss behavior above TC. Those results indicate that the magnetism is associated with Gd3+ ions without any contribution coming from Ni ions. The ρ vs. T curve shows a metallic behavior and decreases linearly with the temperature until 89K. Below that temperature, a more pronounced decrease is observed until the value 48µΩ.cm at 4.2K. That transition shifts towards higher temperatures after a magnetic field is applied and indicates that the magnetic order favors the carrier transport and that the magnetic and transport properties are correlated in this intermetallic.