Mössbauer studies of ferromagnetic metallic glasses under high pressure

An investigation of the M\"ossbauer effect in several ferromagnetic metallic glasses at high pressure is reported. The amorphous alloys studied were of the form (FeₓNi_1-x)M, where M is a combination of the metalloids P, B, Si, or Al, and x varies from 0.34 to 0.47. In these materials the Curie temperatures were observed to decrease with pressure at a rate varying from -0.16 to -0.50 K/kbar. Such behavior is consistent with the simpler itinerant models of ferromagnetism at low pressures, but deviates at the higher pressures, possibly due to inhomogeneities. The magnetic hyperfine spectra were analyzed by decomposing them into hyperfine field distributions, $P(H)$. The average hyperfine fields and their pressure derivatives, qualitatively, behave similar to crystalline Fe-Ni alloys. From the behavior of the pressure dependence of the width of the distributions, one is able to draw some conclusions as to the short-range---versus---long-range nature of the magnetic interactions. The volume dependence of the isomer shifts in these materials suggests an inference as to the near-neighbor coordination of the iron atoms.