Study of the resonance modes of a magnetic tunnel junction-like system

Abstract

The ferromagnetic resonance ͑FMR͒ modes of a magnetic tunnel junction-like system are investigated. Such a system consists of an interfacial ͑F/AF͒ interaction described by an exchange anisotropy field H E and a magnetic coupling of two ferromagnetic layers separated by a nonmagnetic interlayer. The latter interaction is accounted for by bilinear J 1 and biquadratic J 2 coupling strengths. The dispersion relation, the resonant frequency, f, as well as the corresponding mode intensity, I, versus applied field H curves, have been studied. Analytical formulas for the resonance condition and intensity have been derived for the low magnetic coupling/ high exchange anisotropy case. In this situation, the system is found to behave as two uncoupled layers with magnetic characteristics different from those of the initial layers; the effect of the low coupling is to modify the different anisotropies: J 1 contributes to the exchange anisotropy while J 2 modifies the magnetocrystalline anisotropies. For very strong coupling, the system behaves as a single ͑F/AF͒ system with effective exchange and magnetocrystalline anisotropy fields; these fields have been derived as a function of the individual layer magnetic parameters.

Theoretical study of the torque curves in some magnetic multilayer systems

“…Incidentally, some interesting behaviors of the system, at a relatively more fundamental level, are encountered and will be discussed. Some of these results confirm the ones inferred from FMR analysis 27 and from hysteresis curves. 28 The geometry of the system and the energy will be displayed in Sec.…”

“…In previous work, ferromagnetic resonance ͑FMR͒ modes 27 and analytical expressions for the hysteresis curves 28 were investigated for such a system. In the present work some features of the torque curves are studied for this system; included in the model are the effects of the magnetic coupling strength, the exchange anisotropy field ͑H E ͒, the off-alignment angle ␤, and the uniaxial anisotropy fields ͑H A and H B ͒ of the two ferromagnetic layers, with their easy axes making an angle ␦ between them.…”

Static and Dynamic Analysis of Magnetic Tunnel Junctions With Wedged MgO Barrier

“…Moreover, there is an increase in the asymmetry of the precession frequency with respect to zero field, corresponding to the shift in the FL reversal at higher fields. These effects can be simulated by treating FL and RL as a unique layer [15], as previously done for the interpretation of the static hysteresis loop in Fig. 1(c).…”

Resonancia ferromagnética en válvulas de espín: el caso del sistema IrMn(150Å)/Co(50Å)/Ru(32Å)/NiFe(50Å)

“…Además, se puede observar que la aparición de un campo de anisotropía HE = 250 Oe, líneas punteadas, ocasiona que la curva se desplace hacia altas frecuencias o campos bajos, siendo este corrimiento más importante para el modo acústico que para el modo óptico, tal como se discute con más detalle en la Ref. [13]. Adicionalmente, se ha hecho el estudio de cómo la fuerza de acoplamiento afecta a la relación de dispersión.…”