Investigation of structure and magnetic properties of the as-deposited and post-annealed iron nitride films by reactive facing-target sputtering

Structure and magnetic properties of the as-deposited and post-annealed iron nitride films have been investigated systematically. A series of phases containing alpha-Fe, epsilon-Fe(3)N, xi-Fe(2)N and gamma ''-FeN were obtained as nitrogen flow rate (F(N2)) increases from 0.5 to 30 sccm. An increase of the nitrogen concentration in the as-deposited films could be concluded from the phase transition with the increasing F(N2). After being annealed, some of the iron nitride phases are decomposed and gamma'-Fe(4)N appears in the films. The magnetic characteristics are dependent on F(N2), which can be ascribed to the facts that the nitrogen in the films turns the valence states of Fe into Fe(+) or Fe(dipole) with high magnetic momentum or ever H-like bond Fe(+/dipole) with low magnetic momentum based on the bond-band-barrier correlation mechanism. (C) 2011 Elsevier B.V. All rights reserved.