运用微磁学方法讨论了Stoner-Wohlfarth (SW)模型中单畴粒子的矫顽力、临界场、磁滞回线及其磁能积.当外场与粒子易磁化轴的夹角α≤45°时,矫顽力等于临界场；当α ＞45°时,矫顽力比临界场小得多.将SW模型简化成更简单的一致转动模型,计算了由硬磁、软磁两相构成的复合双层膜.计算结果表明,当硬软磁两相的易磁化轴都与外磁场平行(α=0°)时,对于λ(=Ks/Kh)值,其磁滞回线为矩形,即临界场等于矫顽力.随着λ的增大,矫顽力和临界场都增大；当外磁场与硬磁相的易轴平行,与软磁相的易轴垂直(α=90°)时,磁滞回线还是矩形的,但矫顽力和临界场随着λ的增大而减小.%Coercivity, critical magnetic field, hysteresis loop and energy product of the isolated crystallite in the Stoner-Wohlfarth (SW) model have been calculated using a micromagnetic approach. For α ≤45°, which is the angle between the applied magnetic field and easy axis, the coercivity equals to the critical field, while the coercivity is much smaller than the critical field for α >45°. And then, SW model is simplified to a more brief coherent rotation model, where the coercivity and the critical field of the hard/soft magnetic composite bilayers have been calculated. It is found that when both of the e axes for the hard and soft magnetic phases are parallel to the applied magnetic field (α = 0°) , hysteresis loops are rectangular for the same λ ( =Ks/Kh) , i. e. , the critical field e-quals to the coercivity. In addition, both of critical field and coercivity go up as A increases. When the applied magnetic field is parallel to the easy axis in the hard magnetic phase and perpendicular to that in the soft one (α = 90°) , hysteresis loops are still rectangular, but critical field and coercivity decrease with the increasing of A.
展开▼
