Spontaneous magnetostriction of the HeDy2AlFe8Mn8 compound

The thermal expansion behaviors of the unit-cell volume of the Dy2AlFe8Mn8 compound from 104 to 643 K and its spontaneous magnetostrictions are investigated by means of x-ray dilatometry and magnetization measurements. The results show that there exists a negative thermal expansion in the temperature range 150-230 K. The average coefficient of the thermal expansion is α-bar = -5.36 x 10-5 K-1. The spontaneous magnetostrictive deformations from 104 to 235 K have been calculated. The results show that the spontaneous volume magnetostrictive deformation ω s increases from 4.4 x 10-3 at 104 K to 7.1 x 10-3 at 150 K with the temperature increasing, and then decreases with the temperature increasing further. The spontaneous linear magnetostrictive deformation λ c along the c-axis decreases with the temperature increasing while deformation in the basal-plane λ a increases from 0.9 x 10-3 at 104 K to 2.4 x 10-3 at 145 K with the temperature increasing and then decreases with the temperature increasing further