Intergranular Interactions and Thermal Stability in Fe–Ti–N Thin Films

Intergranular interactions and thermal stability factors in Fe-Ti-N thin films were studied as a function of nitrogen content. This was done through: 1) measurements of the isothermal remanence magnetization and direct current demagnetization, coupled with an analysis based on a modified Che-Bertram interaction field model for the intergranular interactions and 2) measurements of the dependence of the coercive force on the holding time for the applied field, coupled with a Sharrock analysis in the case of the thermal stability. The data indicate that the intergranular interactions are mainly exchange dominated for nitrogen levels in the 0-4 at.% range, become primarily magnetostatic for 4-7 at.% nitrogen, and switch back to exchange dominated for higher levels. For nitrogen amounts in the 7-11 at.% range, the thermal stability factors are largest at about 7 at.% and decrease for higher nitrogen amounts. The inferred unit switching lateral size from the Sharrock analysis is about 10-20 times larger than the grain size. The changes in the intergranular interactions and the thermal stability factors with nitrogen content can be qualitatively explained by a grain size effect.