Magnetization reversal through synchronization with a microwave

Abstract

Based on the Landau-Lifshitz-Gilbert equation, it can be shown that a circularly polarized microwave can reverse the magnetization of a Stoner particle through synchronization. In comparison with magnetization reversal induced by a static magnetic field, it can be shown that when a proper microwave frequency is used the minimal switching field is much smaller than that of precessional magnetization reversal. A microwave needs only to overcome the energy dissipation of a Stoner particle in order to reverse magnetization, unlike the conventional method with a static magnetic field where the switching field must be of the order of magnetic anisotropy.

Magnetization switching by microwaves synchronized in the vicinity of precession frequency

“…Microwave-assisted magnetization reversal [1][2][3][4][5][6][7][8][9][10] is a fascinating subject in magnetism for practical applications such as high-density recording. An oscillating field generated by microwaves excites a small-amplitude oscillation of the magnetization in the ferromagnet and significantly reduces the switching field to, typically, half of the uniaxial anisotropy field for an optimized microwave frequency.…”

“…In previous works on microwave-assisted magnetization reversal, [1][2][3][4][5][6][7][8][9][10] the microwave source is isolated from the ferromagnet. Recently, however, an alternative system has been investigated both experimentally and numerically 11,12) in which a spin torque oscillator (STO) is used as the microwave source.…”

Energy dissipation in single-domain ferromagnetic nanoparticles: Dynamical approach

“…Because of its nonlinearity, the precessional motion of the magnetic moment can be very complex. In particular, the circularly polarized magnetic field, whose polarization plane is perpendicular to the anisotropy axis, can generate the periodic and quasiperiodic regimes of * lyutyy@oeph.sumdu.edu.ua † denisov@sumdu.edu.ua precession of the magnetic moment [25][26][27][28]. Moreover, the precessional motion of the magnetic moment induced by the linearly polarized magnet field can exhibit chaotic behavior [29][30][31].…”

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

“…The case when the external fields contain a rotating magnetic field applied perpendicular to the easy axes of nanoparticles has a particular interest. 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.…”