Current-driven domain wall motion enhanced by the microwave field

Abstract

The magnetic domain wall (DW) motion driven by a spin-polarized current opens a new concept for memory and logic devices. However, the critical current density required to overcome the intrinsic and/or extrinsic pinning of DW remains too large for practical applications. Here, we show, by using micromagnetic simulations and analytical approaches, that the application of a microwave field offers an effective solution to this problem. When a transverse microwave field is applied, the adiabatic spin-transfer torque (STT) alone can sustain a steady-state DW motion without the sign of Walker breakdown, meaning that the intrinsic pinning disappears. The extrinsic pinning can also be effectively reduced. Moreover, the DW velocity is increased greatly for the microwave-assisted DW motion. This provides a new way to manipulate the DW motion at low current densities.

Domain wall motion driven by adiabatic spin transfer torque through excitation of nonlinear dynamics

“…Thus we can conclude that the origin of the microwave-assisted DWM is the nonlinear DW width oscillation and the heterodyne between the width oscillation and the microwave field. Despite of the qualitative agreement between the micromagnetic simulation [21,22] and our results, there are quantitative differences in the magnitude and the frequency dependence of the velocity. To reconcile those discrepancies, we stipulate that DWM caused by magnonic momentum transfer [15,16,23] may also be effective in the micromagnetic simulation through the magnonic Doppler effect [24], once the DWM is initiated by the nonlinear DW oscillation.…”

“…To overcome this limitation, various alternatives were suggested, such as the use of spin waves (SWs) [13][14][15][16][17] and thermal gradients [18][19][20]. In addition, it was recently demonstrated, using micromagnetic simulation, that the adiabatic STT can sustain steady DWM with the assistance of a transverse microwave magnetic field [21,22]. The DWM observed there was attributed to the oscillation of the DW width excited by the applied microwave field, but a thorough analysis on the origin of the DWM was not given.…”

Shape-manipulated spin-wave eigenmodes of magnetic nanoelements

“…The magnetization dynamics of nanoscale magnetic structures have attracted considerable attention, both for fundamental reasons and because of their potential technological applications. [1][2][3][4][5][6][7][8][9][10] Over last few years, the dynamic properties of patterned magnetic elements with various shapes and sizes have been studied extensively. [11][12][13][14] Several new features, such as localization and quantization of the spin-wave modes, have been discovered and characterized.…”