A microwave-assisted magnetic recording (MAMR) write head has a spin-torque oscillator (STO) and a ferromagnetic compensation layer between the write pole and trailing shield. The compensation layer is separated from a free layer by a nonmagnetic barrier layer that prevents spin-polarized electrons from the free layer from reaching the compensation layer. The compensation layer may be located between the write pole and the free layer. Electrons become spin-polarized by the compensation layer and are reflected back from the write pole across a nonmagnetic spacer layer. This causes the magnetization of the compensation layer to flip and become antiparallel to the magnetization of the free layer. The compensation layer thus generates a DC offset field that compensates for the negative effect of the DC shunting field from the free layer.