Magnetic and magnetoelastic properties of PrNi5 single crystal.

Abstract

An extensive experimental study by magnetic-resistivity, magnetostriction, and thermal-expansion measurements on a single crystal of the hexagonal ${\mathrm{PrNi}}_{5}$ compound is presented. The magnetoelastic results are quite satisfactorily interpreted within a model involving the crystal-field and quadrupolar interactions acting on the Pr ions and taking into account the Ni contribution. All the unusual features, especially the maxima observed around 15 K in the thermal variations of these properties, arise from crystal-field effects which lead to a nonmagnetic singlet ground state lying about 40 K below the first magnetic level. The induced Ni magnetism, although very small, strongly influences the observed behavior, especially the high-temperature magnetic susceptibility. The magnetoelastic coefficients ${B}^{\ensuremath{\alpha}1}$ and ${B}^{\ensuremath{\alpha}2}$ and the total quadrupolar coefficients ${G}^{\ensuremath{\alpha}}$ and ${G}^{\ensuremath{\epsilon}}$ were determined, leading to the experimental evidence of antiferroquadrupolar interactions between rare-earth ions in ${\mathrm{PrNi}}_{5}$.