Thickness-dependent electronic and magnetic properties of $γ'$-Fe${}_4$N atomic layers on Cu(001)

Abstract

Growth, electronic and magnetic properties of $γ'$-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 $γ'$-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 $γ'$-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 $\hat{I}{¼}_{\mathrm{B}}$/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 $γ'$-Fe${}_4$N atomic layers on Cu(001).

9 pages, 7 figures, 2 tables