  We investigate the formation of stable one-dimensional N\'eel walls in a
ferromagnetic slab with finite thickness and finite width. Taking into account
the dipolar, the exchange and the uniaxial anisotropic crystalline field
interactions, we derive an approximative analytical self-consistent expression
that gives the wall width in terms of ratios between the three different energy
scales of the problem. We also show that, even when the crystalline anisotropy
does not favour the formation of domain walls, they can yet be formed due to
the dipolar interaction and the finiteness of the system. Moreover, using a
Stoner-Wohlfarth approach, we study the magnetization reorientation inside the
domains under the action of an external magnetic field and obtain the
respective hysteresis loops, showing that their shapes change from squared to
inclined as the width of the slab varies. Finally, we discuss possible
applications of this model to describe qualitatively some recent experimental
data on thin films of MnAs grown over GaAs substrates.
