Magnetic flux guiding device with spin torque oscillator (STO) film having negative spin polarization layers in assisted writing application

A device comprising:

• a main pole (MP) that is configured to generate a write field which is directed through a pole tip at an air bearing surface (ABS), and to generate a write gap (WG) field in a down-track direction across a spin torque oscillator (STO) device in a WG, and between a MP trailing side and a trailing shield (TS);
• the trailing shield (TS) with a side at the ABS, and a bottom surface facing the MP;
• and
• the STO device, comprising:
• a first spin polarization preserving layer (ppL1) disposed adjacent to a positive spin polarization (pSP) layer and a flux guiding layer (nFGL) that has a negative spin polarization, wherein the pSP layer is adjacent to the MP;
• a second spin polarization preserving layer (ppL2) disposed adjacent to the nFGL and a first negative spin injection layer (nSIL1);
• and
• a third spin polarization preserving layer (ppL3) disposed adjacent to the nSIL1 and a second negative spin injection layer (nSIL2), wherein the nSIL1 is in contact with both the ppL2 and ppL3, and wherein the nSIL2 is disposed adjacent to a non-spin polarization preserving layer (pxL) contacting the TS, wherein a magnetization of the nFGL is configured to flip to a direction substantially antiparallel to the WG field in response to a current of sufficient current density (J) being applied from the TS to the MP across the STO device, and wherein the nSIL1 and nSIL2 are configured to exert an additive spin torque on the nFGL to cause a magnetization of the nFGL to flip to a direction substantially antiparallel to the WG field, wherein the nSIL1 and nSIL2 exerting the additive spin torque on the nFGL increases a reluctance in the WG and enhances the write field, and wherein the nSIL1 and nSIL2 have a saturation magnetization x thickness (Mst) product substantially less than that of the nFGL.