An amorphous alloy is produced as a ribbon-shaped alloy by a liquid quenching method such as a single roller method. Since there is no crystal grain in an amorphous alloy containing Fe or Co, there exists no crystal magnetic anisotropy, and it has been known that the amorphous alloy exhibits excellent soft magnetism with small magnetic hysteresis, a low coersive force, and a low hysteresis loss. Consequently, an amorphous alloy ribbon containing Fe or Co has been put into practical use in various applications such as a power distribution transformer, a laser power source, and an accelerator, as a soft magnetic material for a magnetic core of various transformers, a chalk coil, various sensors, a saturable reactor, a magnetic switch, etc. Especially, the Fe-based amorphous soft magnetic alloy ribbon has drawn attention as an energy saving material because of its relatively high saturation magnetic flux density Bs, low coersive force, and low iron loss. Among various types of Fe-based amorphous alloy ribbons, an Fe—Si—B amorphous soft magnetic alloy ribbon, which is especially superior in thermal stability, has been broadly used as a transformer magnetic core material.
Since an amorphous soft magnetic alloy represented by an Fe—Si—B amorphous alloy has small magnetic hysteresis and a low coersive force, the hysteresis loss is small. However, it has been known that a broadly-defined eddy-current loss calculated as a difference of an iron loss value minus a hysteresis loss is several tens times to 100 times as high as a classical eddy-current loss obtained by assuming uniform magnetization. This increment is called as anomalous eddy-current loss or excess loss, which is conceivably caused mainly by non-uniform change of magnetization attributable to large width of a magnetic domain of an amorphous alloy.
As a method for reducing the anomalous eddy-current loss of an amorphous alloy ribbon to reduce an iron loss, a scratching method, by which an amorphous alloy ribbon surface is scribed mechanically, a laser scribing method, by which an amorphous alloy ribbon surface is irradiated with laser light for refining a magnetic domain through local melting followed by quenching to solidify, and the like have been known.
Patent Document 1 discloses an amorphous soft magnetic alloy ribbon having undergone a magnetic domain refinement treatment, by which an amorphous soft magnetic alloy ribbon surface is irradiated with pulsed laser light to form amorphous recesses in a linear or dot-line form on the amorphous alloy ribbon surface at predetermined intervals in a longitudinal direction, and describes that the height of a protrusion formed on the amorphous magnetic alloy ribbon around the recess is limited to 2 μm or less. By this means, a low iron loss and a low apparent power can be achieved.