Is the permeability of a ferromagnetic material independent of the magnetic field ? If not, is it more for lower or higher fields ?

Explanation

No, it is evident from the magnetization curve that the intensity of magnetization `I_m` is dependent on the magnetic field intensity H and susceptibility `chi` (on which depends magnetic permeabilility `mu` ). Also, from the slope of the magnetization curve, it is clear that `mu` is greater for lower fields.