Kondo Effect in Amorphous Fe-Pd-Si and Co-Pd-Si Alloys

Abstract

A Kondo-type resistivity minimum has been found in amorphous alloys obtained by rapid quenching from the liquid state and having the compositions ${\mathrm{Fe}}_x{\mathrm{Pd}}_{80-x}{\mathrm{Si}}_{20}$ and ${\mathrm{Co}}_x{\mathrm{Pd}}_{80-x}{\mathrm{Si}}_{20}$, in which $x$ (in at.%) varies from 0 to 7 for Fe and from 0 to 11 for Co. Magnetic measurements indicate that these alloys become ferromagnetic at low temperatures. The resistivity and magnetoresistivity data are analyzed by the existing theories on the $s-d$ exchange interaction. The results demonstrate that the coexistence of the resistivity minimum and ferromagnetism can be explained by the presence of small amounts of paramagnetic ions free from mutual interactions. This result is confirmed by magnetoresistivity measurements. The estimated values for the $s-d$ exchange integral are -0.62eV for the Fe-Pd-Si alloys and -0.42eV for the Co-Pd-Si alloys.