Influence of Tb on easy magnetization direction and magnetostriction of PrFe1.9 alloy*

Abstract

The crystal structures, magnetization, and spontaneous magnetostriction of ferromagnetic Laves phase Pr1 − x Tbx Fe1.9 compounds are investigated in a temperature range between 5 K and 300 K. High resolution synchrotron x-ray diffraction (XRD) analysis shows that different proportions of Tb in Pr1 − x Tb x Fe1.9 alloys can result in different easy magnetization directions (EMD) below 70 K, i.e., [100] with x = 0.0, and [111] with x ≥ 0.1. This indicates Tb substitution can lead the EMD to change from [100] to [111] with x rising from 0.0 up to 0.1. The Tb substitution for Pr reduces the saturation magnetization M s and the magnetostriction to their minimum value when x = 0.6, but it can increase low-field (0 ≤ H ≤ 9 kOe, the unit 1 Oe = 79.5775 A · m−1) magnetostriction when x = 0.8 and 1.0 at 5 K. This can be attributed to the larger magnetostriction of PrFe1.9 than that of TbFe1.9, as well as the decrease of the resulting anisotropy due to Tb substitution at low temperatures.