Low temperature magnetic and magnetostrictive properties in Pr(Fe_1-xCo_x)_1.9 cubic Laves alloys

The structures, spin reorientations, magnetic, and magnetostrictive properties of the polycrystalline Pr(Fe_1-xCo_x)_1.9 (x=0-1.0) cubic laves phase alloys between 5 K and 300 K are investigated. Large low-field magnetostrictions are observed at 5 K in the alloys with x=0.2 and 0.4 due to the low magnetic anisotropies of these two alloys. A large negative magnetostriction of about-1130 ppm is found in PrCo_1.9 alloy at 5 K. The magnetizations of the alloys with 0 ≤ x ≤ 0.6 decrease abnormally at the spin reorientation temperature T_sr, and an abnormity is detected in the alloy with x=1.0 at its Curie temperature T_c (45 K). The substitution of Fe by Co increases the value of T_sr in the alloy with x value increasing from 0.0 to 0.4, and then reduces the value of T_sr with x value further increasing to 0.6.