Auto-oscillation threshold and line narrowing in MgO-based spin-torque oscillatorsS. Cornelissen1, L. Bianchini2, 3, G. Hrkac4, M. Op de Beeck1, L. Lagae1, Joo-Von Kim2, 3, T. Devolder2, 3, P. Crozat2, 3, C. Chappert2, 3 and T. Schrefl4
1 IMEC - Kapeldreef 75, B-3001 Leuven, Belgium, EU
2 Institut d'Electronique Fondamentale, CNRS, UMR 8622 - 91405 Orsay, France, EU
3 Université Paris-Sud - 91405 Orsay, France, EU
4 Department of Engineering Materials, University of Sheffield - Sheffield S1 4DU, UK, EU
received 4 May 2009; accepted in final form 17 August 2009; published September 2009
published online 16 September 2009
We present an experimental study of the power spectrum of current-driven magnetization oscillations in MgO tunnel junctions under low bias. We find the existence of narrow spectral lines, down to 8 MHz in width at a frequency of 10.7 GHz, for small applied fields with clear evidence of an auto-oscillation threshold. Micromagnetics simulations indicate that the excited mode corresponds to an edge mode of the synthetic antiferromagnet.
75.75.+a - Magnetic properties of nanostructures.
72.25.Pn - Current-driven spin pumping.
85.75.-d - Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields.
© EPLA 2009