We have applied magnetic force microscopy (MFM) and spin-polarized scanning
tunnelling spectroscopy (SP-STS) in ultrahigh vacuum (UHV) to study the ma
gnetic domain structure of Co/Au(111) and Gd/W(110), respectively. A new me
asurement mode will be presented which minimizes possible accidental intera
ctions between the probe tip and the sample in UHV-MFM. This allows the inv
estigation of the well known spin reorientation transition of Co films grow
n on Au(lll) at nanometre-scale spatial resolution. Details of domain walls
and the domain structure as a function of CO coverage are studied. Spin-po
larized tunnelling is realized by using an Fe-coated W tip and a sample whi
ch exhibits an exchange-split surface state. Magnetic domain imaging with a
spatial resolution below 20 nm is demonstrated for Gd/W(IIO). The observed
bias dependent spin polarization of Gd(0001) is in good agreement with spi
n-resolved inverse photoemission spectroscopy results.