Vortex state by electric measurements

Electrical determination of vortex state in submicron magnetic elements.

Ajay Gangwar, Hans G. Bauer, Jean-Yves Chauleau, Matthias Noske, Markus Weigand, Hermann Stoll, Gisela Schütz, and Christian H. Back 

Phys. Rev. B 91, 094407 (2015)

AMR spectra measured on a disk shaped sample for (a) up (p=+1) and (b) down (p=−1) polarization of the vortex core for an excitation current of 1.2 mA. The sample design is shown in the inset of (a). By applying a rotating current (counterclockwise or clockwise) the VC polarity can be switched selectively to up or down. A sign change of the AMR voltage signal can be observed for the two polarities. Note that a significant shift of the resonance frequency to higher frequencies is observed at larger bias fields. Also note that the fine structure observed in the spectra does not depend on the VC polarity.

Magnetization reversal in nanodisks

Magnetization reversal by confined droplet growth in soft/hard hybrid nanodisks with perpendicular anisotropy.
J.-P. Adam, S. Rohart, J.-P. Jamet, J. Ferré, A. Mougin, R. Weil, H. Bernas, and G. Faini
Phys. Rev. B 85, 214417 (2012)

(a) Expected spontaneous magnetization M_s variation along the nanodisk radius. (b) PMOKE image difference between the remnant state after a magnetic field pulse (27 mT, 200 ns) and the remnant state after saturation under 500 mT during 5 s.