Coercivity of Melt-Spun Gd100-xFex

We have measured the coercivity of melt-spun Gd_100-xFe_x (0<=x<=40) alloys over the temperature range 2 K<=T<=340 K. Previously performed structural measurements revealed that the system consists of crystalline hcp-Gd grains surrounded by a non-crystalline Gd or Gd-Fe phase composed of Gd_100-x'Fe_x', where x'>x is the iron concentration in the amorphous region. The two-phase structure is responsible for an unusual dependence of the coercivity on temperature in which non-zero coercivity is observed above the hcp-Gd T_c with a peak near 320 K. The coercivity decreases as the hcp-Gd grains order, then increases with decreasing temperature. This behavior is explained by the presence of Fe-rich magnetically correlated regions.