Ultrafast heating-induced magnetization switching in ferrimagnets.
We study theoretically the light-induced magnetization switching in a binary ferrimagnet of the type [Formula: see text], randomly occupied by two different species of magnetic ions. The localized spins are coupled with spins of itinerant electrons via s-d exchange interaction. Model parameters are chosen so that to achieve similarity between magnetic characteristics of the model and those of ferrimagnetic rare-earth-transition metal GdFeCo alloys. The switching is triggered by heating of the itinerant electrons by a laser pulse. The spin dynamics is governed by the cooling of itinerant electrons, exchange scattering, induced by the s-d exchange interaction and spin-lattice relaxation of the itinerant spins with a characteristic time [Formula: see text]. The dynamics of the localized and itinerant spins is described by coupled rate equations. The main conclusion of this study is that the switching occurs only in a certain temperature range depending on [Formula: see text]. For long [Formula: see text] the switching occurs only below the magnetisation compensation temperature TK. For physically reasonable values of [Formula: see text] this temperature range extends from 0 K to [Formula: see text], where [Formula: see text] is slightly higher than the compensation temperature TK. With further decrease of [Formula: see text] this temperature range shifts to temperatures higher than TK.
Ioffe Physical Technical Institute RAS, 194021 St. Petersburg, Russia.
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Gridnev