Magnetic properties of Sm-Co-Cu and Sm-Co-Cu/Co exchange-spring films with high coercivity

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 Sm₂₈Co₃₉Cu₁₃ 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 exchangespring magnet film.