Effect of magnetic field on the structure and magnetic properties of pulse-laser-deposited FePt films

Pulsed laser deposited (PLD) FePt films at different laser wavelength (λ) and out-of-plane external magnetic field (He) were studied. Dependence of composition drifting on laser energy was observed. The composition deviates from the target (equi-atomic) to Pt-rich with increasing λ from 266 to 1064 nm due to the evolution of deposition mechanism from ablation to thermal evaporation. This composition drifting seriously degrades the magnetic properties and increases the ordering temperature of the prepared FePt thin films. Surprisingly, this deviation can be compensated by He. The increment of Fe content is almost proportional to the magnitude of He and inversely proportional to λ. The results provide useful information for the preparation of FePt films by PLD.