A perpendicular magnetic recording write head that a write pole, an
electrically conductive coil coupled to the write pole for generating
magnetic flux in the write pole in the presence of electrical
write current, and a spin torque oscillator (STO) that injects auxiliary
magnetic flux to the write pole in a direction generally orthogonal to the write pole to facilitate
magnetization switching of the write pole. The STO comprises a stack of
layers including electrodes, a pinned ferromagnetic layer having a fixed, a free ferromagnetic layer having a
magnetization free to rotate, and a nonmagnetic spacer layer between the pinned and free
layers. The free layer may be oriented either substantially orthogonal to the write pole or substantially parallel to the write pole, in which latter embodiment a flux guide may be located between the free layer and the write pole for directing the auxiliary
magnetic flux from the free layer to the write pole.