Magnetostrictive Property and Magnetic Domain Structure of Fe-Ga Alloy Single Crystal under Tensile Strain

The saturation value of the magnetostriction curve in the [100] direction of a Fe-Ga alloy single crystal was decreased from 226 to 55 ppm by applying the tensile strain of 533 ppm to the measured direction. By magnetic domain observation using a magneto-optic Kerr effect microscope, a complex structure composed of various magnetic domains was observed under zero applied strain. On the other hand, a stripe structure composed of magnetic domains with the magnetization direction in two kinds of <100> magnetic easy directions parallel to the tensile direction, which were separated by straight 180 degrees domain walls, was observed under the tensile strain of 533 ppm. The characteristic magnetic domain structure due to the tensile strain was successfully observed as a cause of the significant decrease of the saturation value of the magnetostriction curve.