Effect of lattice distortion on magnetic and electronic state of α″-Fe16N2

Abstract

We have studied the correlation of the magnetic moment and electronic state of α″-Fe16N2 with the lattice distortion. The epitaxial (α″+α′)-Fe16N2 films were fabricated on Ag(001) underlayers by sputter beam method. With decreasing the film thickness, the unit cell volume of α″-Fe16N2 increased and distinct enhancement of the magnetic moment up to 2.8μB/Fe atom was found. The precisely determined x-ray diffraction intensity ratio Iα″(002)/Iα″(006) apparently reduced with increase of the unit cell volume. From our theoretical calculations, reduction of Iα″(002)/Iα″(006) means increase of the valency of N atoms in α″-Fe16N2. Therefore, it is considered that increase of the magnetic moment of α″-Fe16N2 is attributed to the charge transfer from N to Fe due to lattice expansion effect. This is the first observation showing close relationship between the electronic state and the magnetic moment of α″-Fe16N2.