原子層積層法によるc軸配向Baフェライト超薄膜の作製  [in Japanese] Deposition of c-Axis-Oriented Ba-Ferrite Ultra-Thin Films by the Alternate Layer Deposition Method  [in Japanese]

We attempted to deposit a hexagonal barium ferrite (BaM) film with a thickness of less than 50nm by using an alternate periodic atomic layer depositon method. BaM films from 11.5 to 115nm thick were deposited at 630℃ on a ZnFe_2O_4(20nm) underlayer of (111) texture. Compared with film deposited by conventional sputtering, the film obtained in this study had excellent c-axis orenetation and crystallinity. Even the BaM film with a thickness of 11.5nm had clear X-ray diffraction peaks from the BaM c-plane. The crystallite size of the film decreased significantly as the thickness of the BaM layer decreased, and the typical crystallite size of the 11.5-nm-thick film was about 25nm. The coercive force of the film in the perpendicular direction, however, decreased markedly as the thickness of the BaM layer decreased below 23nm. A magnetic intermediate layer was produced in the film between the BaM layer and ZnFe_2O_4 underlayer, and thus the film had a double layer structure composed of a BaM layer with perpendicular magnetization and an intermediate layer with an in-plane magnetization.