Magnetic Domain Structure and Magnetostriction of Fe-Ga Single Crystal Grown by the Czochralski Method

The magnetic domain structure on the (0 0 1) plane of an Fe
_16.1
Ga
_83.9
single crystal grown by the Czochralski method was observed by magneto-optic Kerr effect microscopy. In zero magnetic field, four different domain phases appeared, with magnetization in four kinds of '1 0 0 magnetic easy directions on the (0 0 1) plane. That is, the magnetic domain structure in zero field was composed of straight 90° domain walls and stair-like 180° domain walls. When a magnetic field was applied in the [0 1 0] direction, primarily 180° domain walls moved, whereas 90° domain walls did not. A striped domain structure composed of 90° domain walls was formed at a field of about 560 Oe, 180° domain walls having almost disappeared. A single domain structure was obtained by applying a field of about 1980 Oe. Magnetostriction in the [0 1 0] direction on the (0 0 1) plane was only about 10 ppm in a field of about 560 Oe and reached a saturation value of about 153 ppm at a field of about 1980 Oe. This magnetostrictive behavior contributes to the evolution of the magnetic domain structure.