High-quality and impurity-free magnetite surfaces with $(\surd 2\times \surd 2)R45°$ reconstruction have been obtained for the ${\mathrm{Fe}}_3{\mathrm{O}}_4\left(001\right)$ epitaxial films deposited on $\mathrm{Fe}\left(001\right)$. Based on atomically resolved scanning tunneling microscopy images for both negative and positive sample polarity and density-functional-theory calculations, a model of the magnetite (001) surface terminated with Fe ions forming dimers on the reconstructed $(\surd 2\times \surd 2)R45°$ octahedral iron layer is proposed.

The confinement of materials in low-dimensional structures has significant impact on propagating excitations like phonons. Using the isotope-specific ${}^{57}\mathrm{Fe}$ nuclear resonant vibrational spectroscopy we were able to determine elastic and thermodynamic properties of ultrathin Fe films on W(110). With decreasing thickness one observes a significant increase of the mean atomic displacement that goes along with an enhancement of vibrational modes at low energies as compared to the bulk. The analysis reveals that these deviations result from atomic vibrations of the single atomic layers at the two boundaries of the film, while the atoms inside the films vibrate almost bulklike.

The in-plane density of phonon states of clean Fe(110) surface was measured separately for the first, second, and further atomic monolayers using nuclear inelastic scattering of synchrotron radiation. The results show that atoms of the first layer vibrate with frequencies significantly lower and amplitudes much larger than those in the bulk, and that vibrational spectra along two perpendicular in-surface directions are different. The vibrations of the second layer are already very close to those of the bulk. The good agreement of the experimental results and the first-principles calculations allows for detailed understanding of the observed phenomena.

An in-plane spin-reorientation transition occurring during the growth of epitaxial Fe films on W(110) was studied in~situ by using the nuclear resonant scattering of synchrotron radiation. The spin-reorientation transition originates at the Fe/W(110) interface and proceeds via a noncollinear spin structure resembling a planar domain wall that propagates towards the surface with increasing film thickness.