Dynamique ultrarapide de spins 3d et 4f dans des alliages CoDy ferrimagnétique en fonction de la température

International audienceWe report an element-and time-resolved investigation of femtosecond laser induced ultrafast dynamics of the Co 3d and Dy 4f spins in a ferrimagnetic Co80Dy20 alloy as a function of the temperature. We observe that the Co characteristic demagnetization time (τCo) remains nearly constant (~0.2 ps) on increasing the temperature. Conversely, the Dy characteristic demagnetization time (τDy) decreases from ~1 ps to ~0.4 ps with the rise of temperature. Comparing our experimental data with literature shows that τCo and τDy are independent of the alloy composition or the demagnetization amplitude and that τDy scales with the relative temperature T* = TCurie-T