Soft magnetic alloy and plane magnetic element

DETAILED DESCRIPTION To achieve the above object, there is provided, in accordance with the present invention, a soft magnetic alloy film comprising: a fine crystalline phase having an average gain size of 10 nm or less and essentially consisting of Fe of b-c-c structure; and an amorphous phase containing a rare earth element or at least one of the elements, T, Zr, Hf, V, Nb, Ta and W, and O (oxygen) in a large amount, said fine crystalline phase and amorphous phase existing in a mixed state, with the proportion of the fine crystalline phase of Fe of b-c-c structure to the entire structure being 50% or less.
The alloy preferably has a composition of Fe.
sub.
a M.
sub.
b O.
sub.
c ; where M represents at least one of the rare earth elements or a mixture thereof, the composition ratios a, b and c (in atomic %) being as follows: 50.
ltoreq.
a.
ltoreq.
70 5.
ltoreq.
b.
ltoreq.
30 10 .
ltoreq.
c .
ltoreq.
30 a +b +c =100 Further, a composition of Fe.
sub.
d M'.
sub.
e Of is also possible; where M' represents at least one of the elements, Ti, Zr, Hf, V, Nb, Ta and W, or a mixture thereof, the composition ratios d, e and f (in atomic %) being as follows: 45.
ltoreq.
d .
ltoreq.
70 5.
ltoreq.
e.
ltoreq.
30 10.
ltoreq.
f.
ltoreq.
40 d +e -f =100 In accordance with the present invention, there is further provided a plane magnetic element comprising: a substrate, a spiral plane coil, an insulating layer, and a soft magnetic film as described above, laid one on top of the other.