A magnetic recording write head and system has a spin-torque oscillator (STO) located between the write head's write pole and trailing shield. The STO's ferromagnetic free layer is located near the write pole with a multilayer seed layer between the write pole and the free layer. The STO's nonmagnetic spacer layer is between the free layer and the STO's ferromagnetic polarizer. The polarizer may be the trailing shield of the write head, one or more separate polarizer layers, or combinations thereof. The STO electrical circuitry causes electron flow from the write pole to the trailing shield. The multilayer seed layer removes the spin polarization of electrons from the write pole, which enables electrons reflected from the polarizer layer to become spin polarized, which creates the spin transfer torque on the magnetization of the free layer. The multilayer seed layer includes a Mn or a Mn-alloy layer.