Magneto-sensitive wire for magnetic sensor and production method therefor

Abstract

A magneto-sensitive wire (magneto-sensitive body) made of a Co-based alloy having a composite structure in which crystal grains are dispersed in an amorphous phase. The Co-based alloy is, for example, a Co—Fe—Si—B-based alloy, and the total amount of Si and B is preferably 20 to 25 at % with respect to the Co-based alloy as a whole. Preferably, the average diameter of the crystal grains is 70 nm or less and the area ratio of the crystal grains is 10% or less to the composite structure as a whole. The magneto-sensitive wire has a circular cross section and the wire diameter is about 1 to 100 μm. Such a magneto-sensitive wire can be obtained, for example, through a heat treatment step of heating an amorphous wire composed of a Co-based alloy at a temperature equal to or higher than a crystallization start temperature and lower than a crystallization end temperature.