Magnetostrictive strin effects in Pr/sub 6/Fe/sub 11/Ga/sub 3/ alloy

In this research, magnetoelastic properties of Pr
₆
Fe
₁₁
Ga
₃
alloy is studied by magnetostriction and thermal expansion measurements. The phase purity and micro-structure of the sample are studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Temperature dependence of spontaneous volume magnetostriction for this alloy shows an increase as temperature decreases below Curie temperature T
_C
= 320 K through a sequence of two steps. First step appears in the vicinity of T
_C
and second one starts around 280 K. This originated from magnetoelastic effects of short range ferromagnetic order that have a nature of Fe-Fe exchange interaction. The second step is attributed to the gradual long range ordering of magnetic moments which is necessary for low temperature ferrimagnetic phase. At low field region, magnetorestrictive strain is small and smoothly increases for increasing fields. Observed increase in threshold field H
_a
at lower temperatures is attributed to the enhancing magnetocrystalline anisotropy of Pr sublattices. Also, as field increases over H
_a
, magnetic moments gradually rotates with domain walls motion