Switching Magnetization of a Nanoscale Ferromagnetic Particle Using Nonlocal Spin Injection

We have performed nonlocal spin injection into a nanoscale ferromagnetic particle configured in a lateral spin-valve structure to switch its magnetization only by spin current. The nonlocal spin injection aligns the magnetization of the particle parallel to the magnetization of the spin injector. The spin current responsible for switching is estimated from the experiment to be about $200\mu \mathrm{A}$, which is reasonable compared with the values obtained for conventional pillar structures. Interestingly, the switching always occurs from antiparallel to parallel in the particle-injector magnetic configurations, where no opposite switching is observed. Possible reasons for this discrepancy are discussed.

Figure 1

Schematic illustrations of (a) the local spin injection and (b) nonlocal spin injection. (c) SEM image of the fabricated lateral spin-injection device and (d) magnified image around the Py particle.

Figure 2

(a) Nonlocal spin-valve signal with the probe configuration. The solid and dotted lines correspond to the positive and negative field sweep, respectively. (b) The NLSV signal after the pulsed current injection as a function of the current amplitude with the corresponding magnetization configurations.

Figure 3

(a) Nonlocal spin-valve signal with the probe configuration. The solid and dotted lines correspond to the positive and negative field sweep, respectively. (b) The NLSV signal after the pulsed current injection as a function of the current amplitude with the corresponding magnetization configurations.

Figure 4

Schematic illustrations of (a) the induced chemical potential with the negative current injection in the antiparallel configuration and (b) that with the positive current injection in the parallel configuration. (c) Spin-dependent chemical potential inside of the Py particle in parallel (antiparallel) to the Py pad in the negative current. The direction of the injected spin current depends on the polarity of the current and does not depend on the magnetization configuration between the Py pad and the Py particle.