Magnetic properties of Ho measured by a scanning SQUID microscope

We have applied a dc SQUID based microscope to study surface magnetization of a Ho single crystal at 77 K in parallel (up to 0.4 kA/m) and perpendicular (up to 0.1 kA/m) magnetic fields. Magnetization curves and the topographic maps of the magnetic field distribution near the polished surface [0001] of the crystals have been recorded with a spatial resolution better than 50 /spl mu/m. Qualitative evidence for ferromagnetic ordering at the [0001] surface have been found.