Magnetic Properties of Sm–Co–Cu and Sm–Co–Cu/Co Exchange-Spring Films with High Coercivity

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The magnetic properties of Sm–Co–Cu films and Sm–Co–Cu/Co multilayered films prepared by rf-sputtering were investigated. The addition of Cu to Sm–Co film had the effect of decrement of crystallization temperature. The Sm₂₈Co₅₉Cu₁₃ film annealed for 1 h at 623 K showed a reversible demagnetization curve with 82% springback ratio of [Mr′−M(H)]⁄[Mr−M(H)] and a high coercivity of 2480 kA·m⁻¹. This film was found to be an exchange-spring magnet film composed of the hard magnetic phase such as SmCo₅ and Sm₂Co₇ phases and a soft magnetic phase of Co. Sm₂₈Co₅₉Cu₁₃/Co(x nm) multilayered film whose Co thickness was from 0 to 15 nm was also found to be an exchange-spring magnet film.