Help me choose ferrite powder material for motor poles

I am building a multiphase induction motor with a very small rotor <0.5 mm diameter. I need to switch the phases at 100000Hz. The motor size is 2" in diameter. I need high mu ferrite material that is machineable. I need a solid disk 2.5" in diameter. I will machine the disk into wedges for my motor. Any suggestions as to what ferrite powder material would be best. Thank you in advance..