Observation of Magnetic Structures under External Fields by the Photothermally Modulated Stray Field Technique

Magnetic Structures in amorphous Co70(Si+B)23Mn5 and in pure polycrystalline nickel were studied by the photothermally modulated stray field technique. The changes of magnetic domain structure with varying external magnetic field could be observed. For the amorphous alloy, at high magnetic fields structures lying perpendicular to the direction of the external field were detected. The signal of magentic structures observed in nickel showed a locally different dependence on the photothermal modulation frequency. This is interpreted as a depth dependence of the magnetic structures.