Magnetovolume in chromium

The thermal-expansion data of White, Roberts, and Fawcett for Cr and antiferromagnetic CrV alloys measured relative to paramagnetic ${\mathrm{Cr}}_{95}$ ${\mathrm{V}}_5$ up to temperature 700 K are analyzed. The magnetovolume in the ordered state is found to be proportional to the mean-square magnetic moment and their ratio, being proportional to the magnetoelastic coupling, is discussed in relation to the predictions of a theoretical model. Explanations suggested to account for the experimental magnetovolume being somewhat smaller than theoretical estimates include volume dependence of the exchange interaction. Grüneisen parameters associated with magnetic ordering are evaluated and their large values are contrasted with the normal value of order unity obtained by comparing the thermal expansion with the specific heat in the paramagnetic state at temperatures up to 1500 K. The magnetovolume in the paramagnetic state is compared with the mean-square moment obtained from inelastic neutron scattering.