INSP - 4 place Jussieu - 75252 PARIS Cedex 05 - Barre 22-32 - 4e étage, salle 407
Grégoire de Loubens - Service de Physique de l’Etat Condensé (CNRS UMR 3680), CEA saclay
Résumé
Using a magnetic resonance force microscope (MRFM), we provide direct evidence that the ferromagnetic resonance linewidth in a YIG(20nm)|Pt(7nm) disk of 5 µm in diameter changes with the dc current in the Pt layer. The observed effect has the symmetry of the spin Hall effect, and the linewidth can be reduced or enhanced linearly by a factor five, depending on the polarity of the dc current and the orientation of the in-plane bias magnetic field. Compensating completely the damping of the fundamental mode in this sample requires a current density of 3.10^11 A/m^2, in agreement with theoretical predictions. At this critical threshold, the MRFM detects a small change of spontaneous magnetization, a behavior coherent with the onset of an auto-oscillation regime. This is confirmed by direct electrical detection of auto-oscillations in similar samples using spectral analysis.