Spin rotation in ternary ${\mathrm{Ho}}_{0.6}$${\mathrm{Tb}}_{0.4}$${\mathrm{Fe}}_2$

The spin rotation which takes place in the ternary cubic Laves phase compound ${\mathrm{Ho}}_{0.6}$ ${\mathrm{Tb}}_{0.4}$ ${\mathrm{Fe}}_2$ was studied by means of neutron diffraction and Mössbauer-effect spectroscopy. The neutron diffraction measurements were carried out on an aligned powder sample as a function of temperature (4.2-300 K) and external magnetic field (0-8 kOe). Mössbauer spectra of ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ were obtained over a 77-200-K temperature range. The spin rotation in ${\mathrm{Ho}}_{0.6}$ ${\mathrm{Tb}}_{0.4}$ ${\mathrm{Fe}}_2$ is found to take place over the temperature interval 90-140 K. The experimental results enable the determination of the direction of the ferrimagnetic axis as a function of temperature within the spin-rotation interval.