Efficiency of ultrafast laser-induced demagnetization in Gd${}_{x}$Fe${}_{100\ensuremath{-}x\ensuremath{-}y}$Co${}_{y}$ alloys

Efficiency of ultrafast laser-induced demagnetization in Gd $_{x}$ Fe $_{100 - x - y}$ Co $_{y}$ alloys

R. Medapalli, I. Razdolski, M. Savoini, A. R. Khorsand, A. Kirilyuk, A. V. Kimel, Th. Rasing, A. M. Kalashnikova, A. Tsukamoto, and A. Itoh

Phys. Rev. B 86, 054442 – Published 29 August 2012

Abstract

Laser-induced ultrafast demagnetization in ferrimagnetic Gd $_{x}$ Fe $_{100 - x - y}$ Co $_{y}$ thin films was studied experimentally as a function of Gd concentration ( $x = 18$ , 22, 24, 30%, and $y \approx 9$ –10%), pump fluence, and sample temperature. The results showed that the conditions for full demagnetization at the ultrafast time scale in Gd $_{x}$ Fe $_{100 - x - y}$ Co $_{y}$ thin metal films are easily achieved below the magnetization compensation point ( $T_{M}$ ) and, furthermore, when the ratio between Gd and Fe concentrations is not too large. Consequently, the ultrafast demagnetization strongly depends on the initial temperature of these alloys compared to their $T_{M}$ . These results provide further insight into the unconventional ultrafast dynamics of multisublattice metallic magnets.