[T16] Magnetic Materials

[15P-T16-03] Influence of Crystal Structure on Magnetostrictive Properties of Cu_0.8Co_0.2Fe₂O₄

*M. Hisamatsu¹, S. Kosugi¹, S. Fujieda¹, S. Seino¹, T. Nakagawa¹ (1.Osaka University, Japan)

キーワード：magnetostriction, Jahn-Teller phase transition

Cu_xCo_1-xFe₂O₄ ferrites with a cubic spinel structure show negative large magnetostriction at room temperature. For example, when the magnetic field is applied to the measured direction, the -ΔL/L value of the as-synthesized Cu_0.6Co_0.4Fe₂O₄ sharply increases and shows the maximum 354 ppm at about 8 kOe. On the other hand, the -ΔL/L value of the as-synthesized Cu_0.8Co_0.2Fe₂O₄ with a tetragonal spinel structure increases linearly without a maximum even at 24 kOe. In this study, the as-synthesized Cu_0.8Co_0.2Fe₂O₄ was quenched from 1033 K. As a result, the cubic structure was obtained at room temperature. The -ΔL/L value of the quenched sample with the cubic structure sharply increased and showed a maximum at about 2 kOe. Such behavior is similar to those of the as-synthesized Cu_xCo_1-xFe₂O₄ with the cubic structure. Therefore, the magnetostrictive property of Cu_0.8Co_0.2Fe₂O₄ is closely related to the crystal structure.