Evidence of B- and Si-type magnetic relaxations in Co-based amorphous alloys

Abstract

The kinetics of the structural magnetic relaxations (MRs) in the Co-based amorphous alloys has been investigated by magnetic after-effect spectroscopy. The experimental evidence and characterization of two types of MRs in the amorphous ${\mathrm{Co}}_{75}{\mathrm{B}}_{25}$ and ${\mathrm{Co}}_{75}{\mathrm{Si}}_{15}{\mathrm{B}}_{10}$ alloys are rendered in this work. The binary CoB alloy shows only the B-type MR with the most probable energy of the activation energy spectrum $Q*=1.35\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ and the preexponential factor ${\ensuremath{\tau}}_{0}=2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}\phantom{\rule{0.3em}{0ex}}\mathrm{s}$. In the ternary CoSiB amorphous alloy, the additional Si-type MR with $Q*=1.96\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ and ${\ensuremath{\tau}}_{0}=6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}18}\phantom{\rule{0.3em}{0ex}}\mathrm{s}$ occurs. Low-temperature annealing shifts either of the relaxation parameters of both alloys to higher values. Roles of the free volumes, the dimension, and affinity of the B and Si atoms for Co in the MR are discussed.