Efficiency of ultrafast laser-induced demagnetization in GdxFe100-x-yCoy alloys

Laser-induced ultrafast demagnetization in ferrimagnetic GdxFe100-x-yCoy thin films was studied experimentally as a function of Gd concentration (x = 18, 22, 24, 30%, and y approximate to 9-10%), pump fluence, and sample temperature. The results showed that the conditions for full demagnetization at the ultrafast time scale in GdxFe100-x-yCoy 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.