PHASE NOISE ANALYSIS OF A NOISY SPIN TORQUE OSCILLATOR SYNCHRONIZED TO AN EXTERNAL SIGNAL

M. TORTAROLO; C. DIEUDONNÉ; M. QUINSAT; L. BUDA-PREJBEANU; M-C CYRILLE; U. EBELS

Honolulu

Workshop; MMM 2014; 2014

IEEE

Spin transfer oscillations (STOs)[1,2] are promising for microwave applications due to their wide frequency tunning range vs. current, fast modulation rates and compatibility with nanoelectronics. Nevertheless, one of the main issues for these STOs is their relative large linewidth, which can be reduced by phase-locking several oscillators together. For this, we studied the synchronization of an STO to a microwave signal for standard in-plane magnetized oscillators, for which an in-plane precession (IPP) mode is stabilized. The injection locking of this IPP mode to an external microwave current was demonstrated by experiments to occur only at two times the generated frequency (2f) [3]. However, the linewidth in the locked regime was reduced only by a factor of ten, while a reduction to the linewidth of the source was expected. This raises the question on the role of noise on the phase-locking, which leads us to investigate the phase noise and the transient behavior to the locked state for 2f synchronization.