Effect of High- Frequency Driving Current on Magnetization Reversal in Co- Rich Amorphous Microwires
Glass-covered amorphous microwires of nominal composition Co67Fe3.85Ni1.45B11.5Si14.5Mo1.7 (metallic nucleus radius R = 8.6 µm, glass coating thickness T = 0.6 µm), supplied by TAMAG Iberica S.L., were obtained by the Taylor-Ulitovski method [7, 8]. The experiments were performed using a transverse magneto-optical Kerr effect in the axial and circular magnetic field (Fig. 6.1). A DC circular magnetic field (HCIRC) was produced by an electric current flowing through the wire. A DC axial magnetic field (HAX) was produced by a pair of Helmholtz coils. During the experiments, an electric current of frequency f ranging from 4 kHz to 80 MHz and of amplitude up to 8 mA was also applied to the wire. Our experiments show that the electric current of such amplitude does not produce essential Joule heating. A polarized light from the He-Ne laser was reflected from the surface of the microwire to the detector. The beam diameter was of 0.8 mm. For the transverse Kerr effect, the intensity of the reflected light is proportional to the magnetization oriented perpendicularly to the plane of the light. In the present experiments, the circular magnetization is the magnetization that is perpendicular to the plane of the light. Therefore, the light intensity is proportional to the circular projection of the magnetization in the surface area of the wire (see Fig. 6.1).