Ferromagnetic resonance modes of a synthetic antiferromagnet at low magnetic fields

Abstract

One key advantage of antiferromagnets over ferromagnets is the high magnetic resonance frequencies that enable ultrafast magnetization switching and oscillations. Among a variety of antiferromagnets, the synthetic antiferromagnet (SAF) is a promising candidate for high-speed spintronic devices design. In this paper, micromagnetic simulations are employed to study the resonance modes in an SAF structure consisting of two identical CoFeB ferromagnetic (FM) layers that are antiferromagnetically coupled via interlayer exchange coupling. When the external bias magnetic field is small enough to ensure the magnetizations of two FM sublayers remain antiparallel alignments, we find that there exist two resonance modes with different precession chirality, namely y-component synchronized mode and z-component synchronized mode, respectively. These two resonance modes show different features from the conventional in-phase acoustic mode and out-of-phase optic mode. The simulation results are in good agreement with our theoretical analyses.

Recent Advances in Wearable Tactile Sensors Based on Electrospun Nanofiber Platform

“…The diameter of the fibers varies from nanometers to micrometers, and can be well controlled by the polymer characteristics and the electrospinning parameters. [ 134 ] In a specific work, the hydrophobicity of the electrospun TPU nanofiber‐based sensor sheet was thoroughly evaluated by dropping different kinds of liquids including water, artificial sweat and NaOH solution (Figure 12c). [ 60 ] Large contact angles greater than 130° were observed for all kinds of droplets, confirming hydrophobic nature of the fabric sensor, and the hydrophobicity can be maintained even when the fabric sensor sheet is stretched.…”

Terahertz magnetic excitation in antiferromagnets: atomistic spin simulations versus a coupled pendulum model

“…Generally, micromagnetic simulation modeling has been suggested to be an essential tool to gain insight into the of ultrafast spin processes and high-frequency dynamical properties in AFMs [15][16][17] or synthetic AF structures [18][19][20][21][22]. However, the traditional micromagnetics deals with the combination of atomic scale exchange and long-range magnetostatic interactions via the development of a continuum theory, in which the magnetization direction is treated as a continuous function of position in a nanometer spatial variation [23][24][25].…”

Selective damping modulation in a synthetic antiferromagnet induced by spin–orbit torque

“…On the contrary, as the exchange coupling in the SyAFM is not strong, [3][4][5][6] several magnetic states such as the antiferromagnetic, spin-flop, and saturation states can be observed. 9,10) Although the magnetization dynamics in the SyAFM have been intensively studied, [11][12][13][14][15] the dynamics are not understood in several states. Further, the effect of the spin-orbit torque (SOT) driven by spin Hall effect on the SyAFM, [16][17][18][19][20][21][22][23][24][25] which is one of the most important phenomena in spintronics, is unclear.…”

“…As the two magnetizations are antiferromagnetically coupled to each other, there are two resonance conditions for the detected signal, the so-called acoustic (in-phase) and optical (out-of-phase) modes. 10,11,15,19,30) Therefore, we need two combinations of Lorentzian and their derivatives to analyze the detected ST-FMR signal V mix 26,27) as exhibited in Eq. (…”

“…This leads to the injection of ac spin current from one FM to another FM, and vice versa, the so-called mutual spin pumping. 10,15,19,[32][33][34][35][36] Consequently, the magnetizations are damped owing to the pumping effect. In the same spin-flop state in the optical mode, the precessional motions between two magnetizations are at out-of-phase.…”