Finite size effects on spin-torque driven ferromagnetic resonance in spin-valves with a Co/Ni synthetic free layer

Chen, W.
de Loubens, G.
Beaujour, J-M. L.
Kent, A. D.
Sun, J. Z.
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Spin-torque driven ferromagnetic resonance (ST-FMR) is used to study magnetic excitations in Co/Ni synthetic layers confined in nanojunctions. Field swept ST-FMR measurements were conducted with a magnetic field applied perpendicular to the layer surface. The resonance lines were measured under low amplitude excitation in a linear response regime. The resulting resonance fields were compared with those obtained using conventional rf field driven FMR on extended films with the same Co/Ni layer structure. A lower resonance field is found in confined structures. The effect of both dipolar fields acting on the Co/Ni layer emanating from other magnetic layers in the device and finite size effects on the spin wave spectrum are discussed.
Comment: 3 pages, 3 figures
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science