OK
Mu is relative permeability. Mo*Mu is Slope of BH curve. If you guessed the curve of PM in the second quadrant linear, equation is
Mu*Mo=Br/Hc
Mo=4*pi*10^(-7)
For N50 is
Br=1.425
Hc=971 000
And Mu is: 1.167846519
If you want to enter the non-linear characteristic, then you must enter the point by point. In Maxwell Help, you have instructions for how to do it.