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 (alpha) over 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 omega(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 lambda(c) along the c-axis decreases with the temperature increasing while deformation in the basal-plane lambda(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.