膜堆積中と後にArイオン衝撃を加えたFe薄膜の構造と磁気特性(薄膜)

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Three kinds of Fe films, without Ar bombardment [B_<NON>], with Ar bombardment after deposition [B_<AFT>], and with Ar bombardment during deposition [B_<DUR>], were prepared by dual ion-beam sputtering. The relationship between the morphology and the magnetic characteristics of the Fe films was investigated as a function of the film thickness t_F in the wide range between 0.5 and 600 nm. The sputtering voltage and current were fixed at 1200 V and 50 mA, respectively. The Ar bombardments for B_<AFT> and B_<DUR> were carried out at an ion acceleration voltage of 200 V. The features of the film growth were very different according to the type of bombardment. The B_<NON> films changed from an island structure to a layer structure at t_F between 8.0 and 16 nm. The B_<AFT> and B_<DUR> films were revealed smoother surfaces than B_<NON> and echibited a layer structure at t_F above 1.0 nm. However, the saturation magnetization 4πM_s of B_<DUR> abruptly decreased at t_F below 8.0 nm, since the Ar bombardment knocked Fe atoms into the surface region of the glass substrate during the initial growth stage. On the other hand, 4πM_s of B_<NON> and B_<AFT> took an almost constant value of 21.5 kG with a fluctuation of about 5%. The coercivity H_c of B_<AFT> hadlowest value all the films at t_F below 4.0 nm. Tuese results indicate that Ar bombardment after deposition is useful for preparing ultrathin Fe films with excellent soft magnetic properties.
2004-03-01