Nonstoichiometric single phase ${\mathrm{Fe}}_{1-x}\mathrm{O}$ films with ferrimagnetic properties, large saturation magnetization ${(M}_s),$ and low-temperature coercivity ${(H}_c)$ have been prepared and studied. A model on the relation between $M_s$ and the lattice parameter (a) is proposed. The model is based on the existence of 16:5 spinel-type defect clusters, and predicts a linear dependence between $M_s$ and a. The experimental data of $M_s$ versus a is a straight line passing through the point ${(M}_s,a)$ of bulk ${\mathrm{Fe}}_3{\mathrm{O}}_4.$ This fact suggests that ${\mathrm{Fe}}_{1-x}\mathrm{O}$ is the link between the two phases ${\mathrm{Fe}}_3{\mathrm{O}}_4$ and FeO, which have seemingly different physical nature and properties, into one class of materials.

• Received 27 July 1998

DOI:https://doi.org/10.1103/PhysRevB.59.14499