Structure and magnetic properties of amorphousFexSn1−xalloys

Abstract

Amorphous films of ${\mathrm{Fe}}_x{\mathrm{Sn}}_{1-x}$ have been prepared by vapor quenching over a wide range of composition (0.3 < × <0.8). Interference functions have been obtained from electron diffraction. Local magnetic properties have been deduced from Mössbauer-spectroscopy data and compared to bulk magnetization which vanishes at a critical composition $x_{\mathrm{cr}}\simeq 0.35$. Down to $x=0.45\mathrm{}$, the alloys are ferromagnets with a mixture of magnetic and nonmagnetic iron atoms. Hyperfine field distribution on magnetic iron atoms is due to chemical disorder rather than structure effects. Nonmagnetic iron atoms and tin atoms have been found to experience a weak dipolar or a transferred magnetic field, respectively. The temperature dependence of the hyperfine field in iron-rich alloys ($x>\mathrm{}0.53\mathrm{}$) is consistent with predictions of a collective excitation model at low temperature and with a mean-field theory in an intermediate temperature range. A value of the relative distribution width of the exchange integral $\frac{\Delta J}{J}\simeq 0.4$ has been calculated.