Observation of metastable phase separation and amorphous phase in Fe67Co33 alloy thin films synthesized by pulsed laser depositions

• Pulsed laser deposition technique has been employed to grow Fe67Co33 films.
• Films deposited at room temperature exhibited an amorphous and two crystalline phases.
• Both crystalline phases are found to be off stoichiometric compared to the bulk counterpart.
• Films prepared at higher substrate temperature exhibited crystalline single phase bcc structure.
• Magnetic hysteresis is also presented for the films grown at low and high temperatures.

Pulsed laser deposition technique has been used to manipulate the structural order of Fe67Co33 films grown at various substrate temperatures. Films deposited at room temperature exhibited two phases including the stable crystalline phase embedded in the amorphous phase. The crystalline phase separated into two distinct bcc phases as evident from the splitting of (110) reflections, as compared to the bulk counterpart which crystalize into the single phase bcc structure. Both crystalline phases and the amorphous phase were metastable. Films prepared at higher substrate temperatures (∼500 °C), crystallized into the single stable equilibrium bcc structure. Orientation dependent magnetic properties are also presented for the films prepared at both room temperature and higher substrate temperatures. As expected, the easy axes lie parallel to the plane of the substrate due to shape anisotropy. Out of plane magnetization for the films which exhibited short range ordering is found to saturate at smaller field compared to films where single phase bcc structure is stabilized.