Resources for ferromagnetics
Is there a resource with experimental results?


Yes, the permeability figure from the material's datasheet. If \$\mathbf{H}\$ is the uniform field in which you place the material, and \$\mathbf{B}\$ is the field that results from that field plus the magnetic alignment of the ferromagnetic object, then permeability \$\mu\$ is defined by:

$$ \mathbf{B}=\mu \mathbf{H} $$

For real ferromagnetic materials, permeability can be a function of field strength, frequency, temperature, and other variables. The datasheet will elaborate on the more significant variables.

After discussion, it seems you may be wondering what the maximum contribution to the magnetic field a ferromagnetic material could make, if all its magnetic domains were aligned. That is, when all the magnetic domains are aligned, what would the magnetic field of the material be?

When this happens, the material is said to be saturated. You will find this information in the datasheet as well. It is usually specified as the auxiliary field strength (\$\mathbf{H}\$ from above) which is sufficient to fully align all the magnetic domains in the material. Above this field strength, \$\mu\$ effectively drops, since the material can't become any more magnetized.