Nonlinear-dynamical-system approach to microwave-assisted magnetization dynamics (invited)

Abstract

Methods of nonlinear-dynamical-system theory are applied to the study of magnetization dynamics under the action of microwave magnetic fields. In the case of a system with uniaxial anisotropy subject to a circularly-polarized microwave field, the conditions are derived under which the magnetization reversal field is substantially reduced by the application of the microwave field. The dependence of magnetization switching on microwave-field-pulse duration is discussed and analytical expressions are derived for the minimum pulse duration leading to switching. (c) 2009 American Institute of Physic

Frequency dependence of critical switching asteroid of CoCrPt–SiO2 granular film under 50-ns microwave impulse

“…As theoretically proposed by Bertotti et al, the magnetization dynamics under the action of a rf magnetic field can be identified as static switching of the magnetization by adopting a rotating reference frame in which the rf field is stationary. 20,21 In the rotating frame, an effective magnetic field proportional to the frequency of the rf field is generated along the easy axis of magnetization and facilitates magnetization reversal.…”

Resonant suppression of thermal stability of the nanoparticle magnetization by a rotating magnetic field

“…On the one hand, this is because the rotating field plays a key role in the microwave-assisted switching [17][18][19][20][21][22] and, on the other hand, because the corresponding dynamical equations (without accounting the thermal fluctuations) can often be solved analytically. [23][24][25][26][27] Specifically, it has been shown 23 (see also Ref. 28) that the rotating field can induce two types of the stable precessional modes of the magnetic moment, namely, the periodic (P) and quasiperiodic (Q) modes.…”

Switching field modulation of a nanomagnet by resonant microwave spin torque

“…This issue is currently attracting much attention, and the mechanisms implied in the magnetization dynamics during the switching (coherent rotation, vortex core switching, domain wall propagation, etc.) are still open questions, as shown by the important number of experimental [1][2][3][4] and simulation studies [5][6][7][8].…”