Anisotropy and demagnetizing field

[pillow47]

Dear PF,

I'm trying to calculate the anisotropy constant of a ferromagnetic material. Then, of course, I need to worry about the demagnetizing field. However, a book I'm reading claims that we can calculate the anisotropy constant without worrying about the demagnetizing field, if the external magnetic field is applied perpendicular to the easy axis.

Why is this? Why don't you need to worry about the demagnetizing field if your field is perpendicular to the easy axis?

Thanks you very much.

 

[Superposed_Cat]

Uniaxial or Triaxial?