Patent ID: 8021498

Claim:
A magnetic core made of an Fe-based amorphous alloy ribbon, wherein the Fe-based amorphous alloy ribbon has a saturated magnetic flux density B s being not lower than 1.60 T, and a ratio B 80 /B s being not less than 0.90, which is the ratio of a magnetic flux density B 80 generated when an external magnetic field of 80 A/m is applied to the magnetic core in relation to the saturated magnetic flux density B s of the Fe-based amorphous alloy ribbon, wherein the Fe-based amorphous alloy ribbon has a composition that is expressed by a formula T a Si b B c C d wherein T represents Fe, or Fe and at least one element of Co and Ni in an amount of not more than 10% with respect to Fe, in which the suffixes satisfy the expressions of, by atomic percent, 81≦a≦83%, 0<b≦5%, 10≦c≦18%, and 0.2≦d≦3%, and that includes unavoidable impurities; and wherein the Fe-based amorphous alloy ribbon has a carbon segregation layer having a peak position in a range between 2 nm and 20 nm deep from a ribbon surface.