Ferromagnetic resonance in a dilute suspension of uniaxial superparamagnetic particles

A consistent theory of ferromagnetic resonance in a dilute suspension of superparamagnetic particles with uniaxial anisotropy of arbitrary strength is presented. The developed approach is used for studying the high-frequency response of a magnetic fluid at different temperatures. It is shown that in a certain temperature interval the absorption line splits into two components. The width of this interval is essentially dependent on the magnitude of the particle anisotropy. - Highlights: • Consistent theory of ferromagnetic resonance in a dilute ferrofluid is proposed. • At certain temperatures the absorption line of ferrofluid splits into two components. • The effect of splitting is highly sensitive to anisotropy of the dispersed particles.