Angular dependence of the coercive field

Additionally to the reduction of the coercive field with respect to the anisotropy field, the occurrence of nucleation or pinning-depinning may be characterized by the fact that the angular dependence of the coercive field is very different from the one corresponding to coherent rotation. Rather it may be expressed as [ 0] ... 

Figure 1. Angular variation of the normalized coercive field Hc(0)/Ha ( ) Stoner-Wohlfarth model and (o) 1/cos 6 dependence, approximately observed in usual hard magnets. The value of Hc(0) is arbitrary, //C(0)///A = 0.2 has been assumed. At large 6 values, when //c(0) > //sw(0), coherent rotation is favoured again. Inset definitions of the various angles involved in Eqs. 1-3.

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