Dynamics of two coupled vortices in a spin valve nanopillar excited by spin transfer torque

Abstract

We investigate the dynamics of two coupled vortices driven by spin transfer. We are able to independently control with current and perpendicular field, and to detect, the respective chiralities and polarities of the two vortices. For current densities above $J=5.7\ast 10^{7}A/c{m}^2$, a highly coherent signal (linewidth down to 46 kHz) can be observed, with a strong dependence on the relative polarities of the vortices. It demonstrates the interest of using coupled dynamics in order to increase the coherence of the microwave signal. Emissions exhibit a linear frequency evolution with perpendicular field, with coherence conserved even at zero magnetic field.

References in corpus (6)

• Large microwave generation from d.c. driven magnetic vortex oscillators in magnetic tunnel junctions
• Current-driven vortex oscillations in metallic nanocontacts
• Soliton pair dynamics in patterned ferromagnetic ellipses
• Bistability of vortex core dynamics in a single perpendicularly magnetized nano-disk
• Excitation of spin dynamics by spin-polarized current in vortex state disks
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