Low-temperature specific heat of the metallic glasses FexNi80−xP14B6 with x=0,20,40,60,80

Abstract

The specific heat of amorphous ${\mathrm{Fe}}_x{\mathrm{Ni}}_{80-x}{\mathrm{P}}_{14}{\mathrm{B}}_6$ (for $x=0,20,40,60,80\mathrm{}$) has been measured between 0.6 and 30 K. The dependence of ${\Theta }_D\mathrm{}\left(0\right)\mathrm{}$, ${\Theta }_D\mathrm{}\left(T\right)\mathrm{}$, and $N\left(E_F\right)$ on composition has been determined. In addition the paramagnetic sample ($x=0\mathrm{}$) has a large temperature-independent contribution to the specific heat. The ferromagnetic samples ($x=40,60,80\mathrm{}$) have spin-wave terms consistent with the results of Mössbauer and neutron-diffraction studies. The specific heat of the $x=20\mathrm{}$ alloy shows an enhanced linear contribution as well as an exponential contribution at low temperatures raising questions as to its magnetic state.