4 research outputs found
Frequency modulation of spin torque oscillator pairs
The current controlled modulation of nano-contact based spin torque
oscillator (STO) pairs is studied in both the synchronized and non-synchronized
states. The synchronized state shows a well behaved modulation and demonstrates
robust mutual locking even under strong modulation. The power distribution of
the modulation sidebands can be quantitatively described by assuming a single
oscillator model. However, in the non-synchronized state, the modulation
sidebands are not well described by the model, indicating interactions between
the two individual nano-contact STOs. These findings are promising for
potential applications requiring the modulation of large synchronized STO
arrays
Non-linear frequency and amplitude modulation of a nano-contact spin torque oscillator
We study the current controlled modulation of a nano-contact spin torque
oscillator. Three principally different cases of frequency non-linearity
( being zero, positive, and negative) are investigated.
Standard non-linear frequency modulation theory is able to accurately describe
the frequency shifts during modulation. However, the power of the modulated
sidebands only agrees with calculations based on a recent theory of combined
non-linear frequency and amplitude modulation.Comment: 4 pages, 4 figure
Experimental evidence of self-localized and propagating spin wave modes in obliquely magnetized current-driven nanocontacts
Through detailed experimental studies of the angular dependence of spin wave
excitations in nanocontact-based spin-torque oscillators, we demonstrate that
two distinct spin wave modes can be excited, with different frequency,
threshold currents and frequency tuneability. Using analytical theory and
micromagnetic simulations we identify one mode as an exchange-dominated
propagating spin wave, and the other as a self-localized nonlinear spin wave
bullet. Wavelet-based analysis of the simulations indicates that the apparent
simultaneous excitation of both modes results from rapid mode hopping induced
by the Oersted field.Comment: 5 pages, 3 figure