  We studied the influence of a magnetic field (MF) on epitaxial growth and
magnetic properties of Fe(001) films deposited on MgO(001). Thanks to modular
sample holders and a specialized manipulator in our multi-chamber ultrahigh
vacuum system, the films could be deposited and annealed in an in-plane MF of
100 mT. In situ scanning tunnelling microscopy showed that MF had a strong
influence on the film morphology, and, in particular, on the structure of
surface steps. The magnetic properties were studied ex situ using magneto-optic
Kerr effect (MOKE) magnetometry and microscopy. We showed that the moderate
in-plane magnetic field applied during growth has the visible impact on the
magnetic properties. The observed angular dependence of the MOKE loops and
domain structures were discussed based on a magnetization reversal model. In
particular we found that magnetization reversal occurs via 90{\deg} domains and
the reversal differs for the no-field and in-field grown samples, in
correlation with the film morphology.
