Temperature dependence of the magnetostriction in polycrystalline PrFe1.9 and TbFe2 alloys: Experiment and theory

A remarkable magnetostriction λ111 as large as 6700 ppm was found at 70 K in PrFe1.9 alloy. This value is even larger than the theoretical maximum of 5600 ppm estimated by the Steven's equivalent operator method. The temperature dependence of λ111 for PrFe1.9 and TbFe2 alloys follows well with the single-ion theory rule, which yields giant estimated λ111 values of about 8000 and 4200 ppm for PrFe1.9 and TbFe2 alloys, respectively, at 0 K. The easy magnetization direction of PrFe1.9 changes from [111] to [100] as temperature decreases, which leads to the abnormal decrease of the magnetostriction λ. The rare earth sublattice moment increases sharply in PrFe1.9 alloy with decreasing temperature, resulting in the remarkably largest estimated value of λ111 at 0 K according to the single-ion theory