Thickness dependence of magnetization dynamics of an in-plane anisotropy ferromagnet under a crossed spin torque polarizer

Magnetization dynamics of a soft layer (SL) with in-plane anisotropy and under a spin transfer torque (STT) from a perpendicularly magnetized reference layer is investigated. The thickness t of the SL is varied from 1 nm to 4 nm. It is found that uniform and damped oscillations of SL magnetization could be seen at both positive and negative applied current values. The range of each type of magnetization dynamics and the frequency values could be adjusted by changing the current density. The results obtained show the importance of optimizing the SL thickness in addition to its intrinsic properties for spin torque oscillator application with low applied current, high frequency and wide operation range.