A method of determining demagnetizing factor from multidomain hysteresis

摘要: The average internal magnetic field Hi inside a multidomain (MD) grain is the sum of applied Ho and demagnetizing involving factor N grain. It shown that NMD governing MD wall displacements not same as NSD for single-domain (SD) rotations when saturated, determined by ferromagnetic resonance, example. can be from measured hysteresis parameters XO (initial susceptibility), Hc (coercive force), Hcr (remanent coercive Jrs (saturation remanence), JD (magnetization HO = Hcr) one three formulas: (1) XO−1 − Xi−1, (2) (Hc/Jrs) Xi−1 (3) JD−1(Hcr HC) Xi−1. These formulas, which resemble equations derived recently Smith Merrill, reduce to conventional approximations intrinsic susceptibility Xi dJ/dHi → ∞. In order use exact must estimated independently assuming XiHc ≈ constant. Using measurements 2200-A cubes magnetite, should theoretically have two-domain or three-domain structure, calculated about 2, in satisfactory agreement with predicted values half 4π/3 cube.