PtMn反強磁性膜と強磁性膜の交換結合 (<特集>多層膜・人工格子・グラニューラー)

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Exchange coupling between antiferromagnetic Pt-Mn and ferromagnetic films was investigated. By varying the Pt-Mn composition in bilayer NiFe/PtMn films, values of the exchange-coupling field (H_<ex>) were obtained in the Pt composition range between 4 and 24 at%, both in the asdeposited state and after annealing. In the Pt composition range between 44 and 54 at%, H_<ex> values were obtained only after annealing. We precisely investigated films with a Pt_<48>Mn_<52> at% composition annealed at 190-250℃, and showed that the H_<ex> values of films coupled with 2-4 nm NiFe after annealing at 230℃ for 4 h were 500-680 Oe. The blocking temperatures of the films coupled with 3 nm NiFe, 20 nm NiFe, 4 nm Co, and 20 nm Co showed almost the same value, 380℃. The exchange-coupling energies at room temperature of bilayer 20 nm Co/30 nm PtMn and 20 nm NiFe/30 nm PtMn were 0.32erg/cm^2 and 0.16 erg/cm^2, respectively. The H_<ex> of the 3 nm Co layers either on top of or below PtMn layers showed large values of more than 600 Oe. PtMn films also showed excellent corrosion resistance, and are therefore suitable antiferromagnetic layers for use in spin-valve heads, especially dual-spin-valve heads.
1997-04-15