Measurements of stray magnetic fields of amorphous microwires using scanning microscope based on superconducting quantum interference device

A scanning high-temperature superconducting quantum interference device microscope with spatial resolution of about 50 μm and sensitivity of 2 μOe/Hz1/2 has been used to study stray magnetic fields of glass-coated microwires with compositions Fe74B13Si11C2 and Co74B13Si11C2 at T=77 K. The stray field images have been obtained within a soft magnetic shield (residual magnetic field, Hr<1 mOe), as well as with applied magnetic field within the range of ±50 Oe. For a Fe-rich microwire, a simple two-pole structure has been observed in the ground state, whereas for a Co-rich microwire the ground state corresponds, probably, to a domain structure with alternating magnetic poles along the wire length.