Analytical expressions for the ferromagnetic resonance mode intensity and linewidths for a weakly coupled magnetic tunnel junction system

摘要

Ferromagnetic Resonance mode intensity, I, field linewidth, Delta H, and frequency linewidth, Delta f, have been investigated for a weakly coupled magnetic tunnel junction (MTJ) system. The analysis applies for a coupled trilayer, i. e., two ferromagnetic thin films separated by a non magnetic thin film and for a MTJ system consisting of the trilayer and an antiferromagnetic layer. For this particular weakly coupled system, analytical expressions for I, Delta H, and Delta f have been determined. The linewidth expressions can be separated into the parts characterizing the individual thin films and magnetic coupling dependent parts; the mode linewidths can be viewed as those of uncoupled thin films with equivalent damping parameters. The intensity and the linewidths are discussed for different applied magnetic fields, for the saturated and unsaturated systems, and for the two types of coupling. It will be shown how the mode intensity behavior can be used as a probe to distinguish the ferromagnetic from the antiferromagnetic coupling. Published by AIP Publishing.