We present atomistic spin dynamics modeling of thermally induced magnetization switching (TIMS) of disordered ferrimagnetic TbCo alloys varying the Tb concentration, laser pulse fluence, and its duration. Our results indicate that deterministic TIMS occurs in a wide range of Tb concentrations and at large laser fluences with a pulse duration of 50 fs. We furthermore demonstrate that the occurrence of the transient ferromagneticlike state is necessary, but after first reversal, the system may switch back. The presence of a magnetization compensation point or going through it is shown not to be required. With the increase of the laser pulse duration TIMS becomes stochastic so that for a 1 ps laser pulse width and beyond the deterministic heat-assisted AOS does not exist.

This work was supported by the Spanish Ministry of Economy and Competitiveness under the Grants MAT2013-47078-C2-2-P, FIS2016-78591-C3-3-R, and by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 281043, femtospin. T. A. Ostler gratefully acknowledges the Marie Curie incoming BeIPD-COFUND fellowship program at the University of Liège.