抄録
Epitaxial thin films of Ni-ferrite were prepared on C-plane sapphire substrates by pulsed laser deposition in high vacuum. When deposited at oxygen pressures of greater than 1 × 10−6 Torr, the films crystallized in NaCl-type crystal structure at Ts≤100°C, while in spinel-type crystal structure at Ts≥150°C. The low temperature growth of the ferrite thin films was ascribed to the high kinetic energy of ablated particles at low oxygen pressures and to the low deposition rate of the films. X-ray phi scan and reflection high-energy electron diffraction analysis showed that the spinel ferrite films epitaxially grew with (111) texture normal to the film plane and in-plane alignment of NiFe2O4 [110] parallel to sapphire [1100]. The films had an excellent crystallinity as well as a good surface smoothness as grown at Ts ≥ 200°C.
