Electric-field assisted depinning and nucleation of magnetic domain walls in FePt/Al2O3/liquid gate structures
Résumé
We present a magneto-optical Kerr effect study of the magnetization reversal in a FePt/Al2O3 structure under electric (E) fields generated in a liquid electrolyte environment. The FePt film was partially covered with a thick Al2O3 layer that allowed for the study of a pinned domain wall between two regions of different coercive field. Depinning of the trapped domain wall into the region of higher coercivity was achieved by applying positive gate voltages during the magnetic field ramp and prevented in the presence of negative gate voltages. Moving from positive to negative gate voltages produced, in addition, an increase (decrease) in the number (size) of reverse domains in the high anisotropy region. This effect has been associated to an E-field induced decrease of the saturation field. Using a liquid gate to assist domain wall depinning as presented here can be used for the control of multiple pinning structures in parallel.