136 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
Power and linewidth of propagating and localized modes in nanocontact spin-torque oscillators
Integrated power and linewidth of a propagating and a self-localized spin
wave modes excited by spin-polarized current in an obliquely magnetized
magnetic nanocontact are studied experimentally as functions of the angle
between the external bias magnetic field and the nanocontact plane.
It is found that the power of the propagating mode monotonically increases with
, while the power of the self-localized mode has a broad maximum near
deg, and exponentially vanishes near the critical angle
deg, at which the localized mode disappears. The linewidth of
the propagating mode in the interval of angles deg, where only
this mode is excited, is adequtely described by the existing theory, while in
the angular interval where both modes can exist the observed linewidth of both
modes is substantially broadened due to the telegraph switching between the
modes. Numetical simulations and an approximate analytical model give good
semi-quantitative description of the observed results.Comment: 8 pages, 6 figure
Controlled skyrmion nucleation in extended magnetic layers using a nanocontact geometry
We propose and numerically simulate a spintronic device layout consisting of a nanocontact on top of an extended Co/Pt bilayer. The interfacial Dzyaloshinskii-Moriya interaction in such bilayer systems can lead to the possible existence of metastable skyrmions. A small dc current injected through the nanocontact enables the manipulation of the size as well as the annihilation of an initially present skyrmion, while ps-long current pulses allow for the controlled nucleation of single skyrmions underneath the nanocontact. The results are obtained from micromagnetic simulations and can be potentially used for future magnetic storage implementations
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
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