Multidomain and single-domain relations between susceptibility and coercive force

摘要: Abstract Theoretically, multidomain (MD) initial susceptibility (χ0)init and coercive force Hc are related by 1/(χ0)init = k−1Hc/js + N, in which js is spontaneous magnetization Js normalized to its room-temperature value Js0, N a demagnetizing factor, k sample-dependent constant of the order 45 emu cm−3 (4.5 × 104 A m−1) for magnetite. The corresponding single-domain (SD) relation k−1Hc/js, with 0.319Js0 (for magnetite ≈ 150 cm−3). slopes intercepts linear plots Hc/js data measured at different temperatures should thus reveal domain structure give MD case. We have tested equations using SD small magnetites, maghemites titanomaghemites. In most cases relations were linear, but many variance theory. Some discrepancy between theory experiment may result from mixtures material non-uniaxial anisotropies, due thermal fluctuations. develop generalized method fluctuation analysis (TFA) deal such effects excitation range below unblocking temperature.