The magnetization dynamics of a two-sublattice ferrimagnet near the angular momentum compensation point
A.A. Galkin Physics and Technology Institute of the National Academy of Sciences of Ukraine 72 R. Luxemburg Str., Donetsk 83114, Ukraine
Received June 6, 2013
The high-frequency properties of a two-sublattice ferrimagnet at temperatures near the angular momentum compensation point TL are studied. The diagram technique for spin operators, as well as the analytical expressions applicable in the total temperature interval of magnetic ordering are used. It is shown that near TL the longitudinal magnetic fluctuations substantially affect the resonance properties of the magnet, so that temperature behaviors of in-phase and opposite-phase precessions of sublattice magnetizations are different. With approaching TL the frequency of the in-phase precession increases simultaneously with a significant increase of the line width, while the frequency of the opposite-phase oscillation substantially decreases, so that the both types of oscillations are equal. The results obtained are important for understanding of microscopic mechanisms of magnetization reverse by ultrashort laser pulses in rare-earth ferrimagnets.