Growth, electronic and magnetic properties of $\gamma'$-Fe$_{ 4}$N atomic layers on Cu(001) are studied by scanning tunneling microscopy/spectroscopy and x-ray absorption spectroscopy/magnetic circular dichroism. A continuous film of ordered trilayer $\gamma'$-Fe$_{ 4}$N is obtained by Fe deposition under N$_{ 2}$ atmosphere onto monolayer Fe$_{ 2}$N/Cu(001), while the repetition of a bombardment with 0.5 keV N$^{ +}$ ions during growth cycles results in imperfect bilayer $\gamma'$-Fe$_{ 4}$N. The increase in the sample thickness causes the change of the surface electronic structure, as well as the enhancement in the spin magnetic moment of Fe atoms reaching $\sim$ 1.4 $\mu_{ \mathrm B}$/atom in the trilayer sample. The observed thickness-dependent properties of the system are well interpreted by layer-resolved density of states calculated using first principles, which demonstrates the strongly layer-dependent electronic states within each surface, subsurface, and interfacial plane of the $\gamma'$-Fe$_{ 4}$N atomic layers on Cu(001).
Categories: cond-mat.mtrl-sci