Low-temperature specific heat study of amorphous Co1-xBxalloys

Low-temperature specific heats for amorphous Co 1-x B x alloys (x=0.16, 0.18, 0.20, 0.22, 0.26 and 0.30) have been measured in the temperature range between 1.5 and 6K. The results are found to fit well to the equation C= gamma T+ alpha T 3 + sigma s T 3 2/+ sigma n T -2 . The electronic specific heat coefficient gamma shows only a weak composition dependence and is close to the value for pure HCP Co. This suggests that the density of states near the Fermi level does not change appreciably with varying B content. The Debye temperature always exceeds 300K and increases monotonically with increasing B content. The observed nuclear specific heat coefficient sigma n allows the effective magnetic field H eff at the Co nuclear site to be determined. The value of 114 kOe mu B -1 is in good agreement with the reported valued derived from the NMR experiment on the amorphous Co 75 B 25 alloy.