Time-domain stability of parametric synchronization in a spin-torque nano-oscillator based on a magnetic tunnel junction

Abstract

We report on time-domain stability of the parametric synchronization in a spin-torque nanooscillator (STNO) based on a magnetic tunnel junction. Time-domain measurements of the instantaneous frequency (fi) of a parametrically synchronized STNO show random short-term unlocking of the STNO signal for low injected radio-frequency (RF) power, which cannot be revealed in time-averaged frequency domain measurements. Macrospin simulations reproduce the experimental results and reveal that the random unlocking during synchronization is driven by thermal fluctuations. We show that by using a high injected RF power, random unlocking of the STNO can be avoided. However, a perfect synchronization characterized by complete suppression of phase noise, so-called phase noise squeezing, can be obtained only at a significantly higher RF power. Our macrospin simulations suggest that a lower temperature and a higher positive ratio of the field-like torque to the spin transfer torque reduce the threshold RF power required for phase noise squeezing under parametric synchronization.

Large Damping-like Spin–Orbit Torque and Improved Device Performance Utilizing Mixed-Phase Ta

“…Figure e shows the simulated phase noise ( S ϕ ) for mixed-phase (black line) and β-phase Ta (red line) at the threshold condition. Both the plots show the typical 1/ f 2 phase noise behavior. , It is found that the β-phase Ta system shows a much higher phase noise compared to mixed-phase Ta. This also leads to higher linewidth for the β-phase Ta system as shown in the inset of Figure e.…”

Electrically connected spin-torque oscillators array for 2.4 GHz WiFi band transmission and energy harvesting

“…The phase noise in both series and parallel configurations shows a typical 1/ f 2 behavior of STOs due to the thermal fluctuations and π-phase slips, which indicates a partial phase locking. The linewidth can be reduced to the source linewidth by injection or sub-harmonic locking as seen in vortex STOs 44 if 1/ f 2 phase noise is completely suppressed 25 , 45 . The main reason for this limitation is a higher phase noise in uniformly magnetized STOs which might require a much higher rf power for the complete phase noise suppression 25 , 45 .…”

“…The linewidth can be reduced to the source linewidth by injection or sub-harmonic locking as seen in vortex STOs 44 if 1/ f 2 phase noise is completely suppressed 25 , 45 . The main reason for this limitation is a higher phase noise in uniformly magnetized STOs which might require a much higher rf power for the complete phase noise suppression 25 , 45 . For the series configuration in Fig.…”