X-ray diffraction and transmission electron microscopy measurements of melt-spun Gd100-xFex (0 x 40) and inert-gas condensed/compacted samples (3.8 x 12.7) reveal a structure of crystalline hcp-Gd grains surrounded by a non-crystalline Gd1-xeffFexeff phase, where x eff > x is the effective iron concentration within 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 Tc 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 magnetically correlated Fe-rich regions.
Bibliographical noteFunding Information:
This work was supported by the National Science Foundation ( DMR-0504706 (UNL), DMR-0504177 (UNI) and DMR-0706593 (UNF)) and the US Department of Energy ( DE-FG02-06ER46264 ). Work at the Ames Laboratory was supported by the Department of Energy, Office of Basic Energy Sciences, under Contract no. DE-AC02-07CH11358.
- Gadolinium-iron alloy