Modeling of Temperature Dependence of Magnetization in TbFe Films — An Atomistic Spin Simulation Study

In this paper, we performed spin simulations at atomistic level to study the temperature dependent properties of perpendicularly magnetized TbFe thin films. The crystallographically amorphous feature of TbFe ferrimagnetic alloys is modeled by using a lattice system with disordered site occupation of rare earth (RE) and transition metal (TM) spins. The simulated Curie temperature ([Formula: see text]) is consistent well with the mean-field approximation theory. With the increase of Tb concentration, the [Formula: see text] decreases almost linearly, whereas the magnetization compensation temperature ([Formula: see text]) increases gradually until the [Formula: see text] value is reached. The inter-sublattice exchange coupling strength [Formula: see text] between the RE and TM atoms can significantly affect [Formula: see text], but has less impact on [Formula: see text]. With the increase of Tb concentration, the TbFe sample of high [Formula: see text] exhibits a much faster increase in [Formula: see text] than the sample with low [Formula: see text]. Moreover, we have tested the simulation code to model the laser pulse induced ultrafast nonequilibrium spin dynamics. As an example, the femto-second pulse laser induced demagnetization and recovery process is clearly reproduced. These features are in a good agreement with the experiments, indicating that the simulation model can capture the basic physics in describing the high temperature dependent magnetic property as well as the ultrafast spin dynamics.