Zero-dc-field rotation-direction-dependent magnetization switching induced by a circularly polarized microwave magnetic field

Abstract

Magnetization switching of high-anisotropy nanomagnets by a small magnetic field is a key challenge in developing future magnetic nanodevices. In this paper, we experimentally demonstrate magnetization switching of a perpendicularly magnetized nanomagnet induced solely by an in-plane circularly polarized microwave magnetic field. Applying a microwave field with an amplitude below 5% of the anisotropy field induces large ferromagnetic resonance excitation, which results in magnetization switching even in the absence of a dc field. This kind of magnetization switching is induced by a microwave field with a duration of 0.5 ns and is clearly dependent on the rotation direction of the microwave field.

Synchronization and chaos in a spin-torque oscillator with a perpendicularly magnetized free layer

“…should be added to the magnetic field H. The amplitudes of the microwave field in the x and y directions are denoted as H x ac and H y ac , respectively, whereas the phase difference between them is φ ac . We note that superposition of two microwave fields with the phase difference as such is realized experimentally by using two coplanar wave guides [49]. In Sec.…”

Thermal activation on microwave-assisted magnetization switching in Co/Pt nanodot arrays

“…MAS has been of great interest as a key technology of microwave-assisted magnetization recording. [1][2][3][4] Therefore, MAS has been studied extensively, both experimentally [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] and theoretically. [21][22][23][24][25][26][27][28] Magnetization behavior under a microwave field has been often explained by a macrospin model based on the Landau-Lifshitz-Gilbert (LLG) equation in a rotating frame.…”

Synchronized, periodic, and chaotic dynamics in spin torque oscillator with two free layers

“…The development in the magnetic recording technology faces a serious issue because the magnetic field produced in conventional recording method solely using a direct field is not sufficient enough in next generation high-density recording system. Microwave assisted magnetization reversal (MAMR) is a new scheme of magnetic recording, where the microwave emitted from an STO contributes to the reduction of the direct magnetic field necessary for the recording [26,27,28,29,30,31,32,33,34,35,36]. The latest design of the STO for MAMR consists of two in-plane magnetized ferromagnetic layers called field-generation layer and spin-injection layer [37].…”