Magnetoelastic properties ofRZnequiatomic compounds

Abstract

The magnetoelastic properties of the ferromagnetic cubic compounds of heavy rare earths with zinc ($R\mathrm{Zn}$) are investigated. Lattice distortions occuring below the ordering point are particularly strong when tetragonal: For instance, DyZn exhibits at low temperature a spontaneous tetragonal strain expressed as $\frac{c}{a}-1=+8.1\mathrm{}\times {10}^{-3\mathrm{}}$. All of these magnetoelastic properties are chiefly due to the crystalline electric field splitting of the ground-state $J$ multiplet. But the tetragonal distortion observed in GdZn below the ordering point reveals pseudodipolar magnetoelastic effects to be important also; this contribution is taken into account for all the compounds. From our strain gauges and capacitance dilatometer experiments we deduce the one-ion and two-ion magnetoelastic coefficients across the series. The former ones are compared with determinations from ultrasonic measurements and their variation through the series is interpreted in terms of crystal-field theory. Finally, an attempt was made to connect these coefficients to the present knowledge of the conduction band in these CsCl-type intermetallic compounds.