1/f-type noise in a biased current perpendicular to the plane spin valve: A numerical study

We add the spin momentum-transfer torque to the stochastic Landau–Lifshitz equation and use it to study the noise spectrum as a function of the current and easy axis field for configurations close to equilibrium. The current perpendicular to the plane structure is biased by a constant field perpendicular to the polarization axis of the pinned layer. We show that this structure can exhibit large 1/f-type noise for frequencies in the microwave regime. This 1/f noise is not due to the spin torque. The spin torque can only change the amplitude of the noise.