Relaxation Losses of Magnetic Excitations in Nanoscale Films of Yttrium Iron Garnet

Relaxation losses of magnetic excitations in nanoscale films of Y 3 Fe 5 O 12 (YIG) were studied. The films were obtained by laser molecular-beam epitaxy (LMBE). Ferromagnetic resonance linewidth Δ H was found to increase sharply as the temperature decreased from 300 to 77 K. The observed growth of Δ H is explained by typical relaxation processes caused by the presence of Fe 2+ ions. This effect is not observed in thick films of YIG grown by liquid-phase epitaxy and containing Pb 4+ ions, and, hence, we have concluded that the presence of acceptor ions in YIG films obtained by LMBE will facilitate decreasing the concentration of Fe 2+ ions and, a result, diminishing relaxation losses.