Mössbauer study of an amorphous magnetic solid containing Cr

Abstract

A Cr-containing transition metal based amorphous magnetic solid (${\mathrm{Fe}}_{32}$${\mathrm{Ni}}_{36}$${\mathrm{Cr}}_{14}$${\mathrm{P}}_{12}$${\mathrm{B}}_{6}$) has been studied by $^{57}\mathrm{Fe}$ M\"ossbauer spectroscopy in both its amorphous and crystalline states. The magnetic ordering temperatures of ${T}_{C}=249, 254, \mathrm{and} 238$ K have been determined for samples from three batches. In the amorphous state at $T>{T}_{C}$, well-defined quadrupole spectra are observed. At 4.2 K, the hyperfine-field distribution $P(H)$ is characterized by a two-maxima function of $H$. It is shown that the high-field component is due to Fe with mainly Fe and Ni as neighbors, whereas the low-field component originates from Fe atoms with Cr neighbors. The temperature dependence of $P(H)$ is studied at various temperatures and unusual features have been observed. In both the amorphous and the crystalline states of the sample, a noticeable amount of Fe is found to be weakly coupled. This is consistent with the results of the magnetic measurements and provides an explanation of the resistivity anomaly.