2 research outputs found
Critical velocity for the vortex core reversal in perpendicular bias magnetic field
For a circular magnetic nanodot in a vortex ground state we study how the
critical velocity of the vortex core reversal depends on the magnitude
of a bias magnetic field applied perpendicularly to the dot plane. We find
that, similarly to the case = 0, the critical velocity does not depend on
the size of the dot. The critical velocity is dramatically reduced when the
negative (i.e. opposite to the vortex core direction) bias field approaches the
value, at which a \emph{static} core reversal takes place. A simple analytical
model shows good agreement with our numerical result.Comment: 4 pages, 2 figure
Microwave signal emission in spin-torque vortex oscillators in metallic nanowires: Experimental measurements and micromagnetic numerical study
We report on microwave oscillations induced by spin-transfer torque in metallic spin valves obtained by electrodeposition of Co-Cu-Co trilayer structures in nanoporous alumina templates. Using micromagnetic calculations performed on similar spin-valve structures it was possible to identify the magnetization dynamics associated with the experimentally determined microwave emission. Furthermore it appears that in our particular geometry the microwave emission is generated by the vortex gyrotropic motion which occurs in, at least, one of the two magnetic layers of our spin-valve structures. Microwave emission was obtained in the absence of any external magnetic field with the appropriate magnetization configuration. © 2012 American Physical Society