The effect of structural relaxation on the Curie temperature of Fe based metallic glasses

The Curie temperature, T
c
, of (Fe
100-x
M
x
)
0.75
P
0.16
B
.06
Al
.03
glasses with M = Ni, Mo or Cr were measured. T
c
of the glasses increases monotonically with annealing temperature T
a
. The rate of increase,
dT_{c}/dT_{a}
, however, exhibits maxima at
T_{a} = 500
and 600 K; temperatures at which the structural relaxation spectra also exhibit peaks. At lower temperatures, T
c
increases at rates that are greater than those of structural relaxation processes. Since the low and high temperature relaxation peaks may be attributed to local atomic regroupings and cooperative atomic rearrangements, respectively, the present results imply that the magnetic properties of metallic glasses are more sensitive to changes in local atomic arrangement than to longer ranged correlations. The change in T
c
is larger for the Ni containing glasses than for glasses containing Mo, Cr, or Mn.