Influence of Stress and Strain on $L 1_{0}$ -Ordered Phase Formation in FePt Thin Film

Effects of stress and strain in FePt thin film on L1
₀
ordering are investigated by employing single-crystal substrate of which lattice mismatch with FePt crystal is varied in a range from -10.3% to +0.8% for 10 nm thick FePt thin film. Thin films are prepared under different conditions; direct deposition at 600 °C, two-step process consisting of 200 °C deposition followed by 600 °C annealing, and the two-step process with MgO cap layer formed on top of the FePt layer at 200 °C. Formation of L1
₀
-FePt(001) crystal and L1
₀
ordering is enhanced on a substrate with larger negative lattice mismatch, though the lattice mismatch with substrate is decreased greatly by introduction of misfit dislocation and by lattice bending in FePt material. The lateral in-plane strain in FePt material associated with several factors: substrate material, film morphology, and cap layer has given a strong influence in L1
₀
-ordered phase formation in FePt thin film.