Magnetic and hyperfine interactions in amorphous Fehyphen;P alloys

摘要

Amorphous alloys FexP100minus;xhave been fabricated by rf sputtering in the composition range 50le;xle;75. Magnetic ordering temperatures were determined using thermogravimetric analysis (forx=75) and by zerohyphen;velocity thermal scanning (for 50le;xle;71). Ordering temperatures are depressed from those of the corresponding crystalline phases and range between 550 K forahyphen;Fe75P25and 10 K forahyphen;Fe50P50. The Mouml;ssbauer spectra at 8 K of alloys withxle;71 all had a central unsplit line and broad, essentially featureless wings, indicating the coexistence of magnetically ordered and nonmagnetically ordered regions. The spectrum ofahyphen;Fe75P25consisted of six broad lines, indicating that this composition is magnetically more homogeneous. Hyperfinehyphen;field distributionsP(H) and mean isomer shifts (IS), determined using Windowrsquo;s method, show that mean hyperfine fields have an essentially linear dependence on concentration and, by extrapolation, vanish atxsim;46. The IS values at 293 K, however, have only small variations with composition and a weak maximum atx=67, whereas at 8 K the composition dependence is larger and there is a minimum atx=67. This behavior suggests a structural alteration whose nature is, as yet, unclear.