We measure phase noise from the zero crossings of the voltage vs. time waveform of a spin torque nanocontact oscillating in a vortex mode. The power spectrum of the phase noise varies with Fourier frequency f as 1/f2, consistent with frequency fluctuations driven by a thermal source. We compare the linewidth due to phase noise with that measured using a spectrum analyzer. A phase-locked loop reduces the phase noise for frequencies within its 3 MHz bandwidth.
Citation: Applied Physics Letters
Pub Type: Journals
spin torque, phase noise, phase-locked loop