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R. Moreno, S. Khmelevskyi, O. Chubykalo-Fesenko:
"Role of exchange parameters for ultrafast thermally induced magnetization switching in ferromagnets";
Physical Review B, 99 (2019), 1844011 - 1844018.

The ultrafast deterministic thermally induced magnetization switching (TIMS) under the excitation by a
one-shot femtosecond laser pulse has been widely achieved in disordered ferrimagnetic alloys such as GdFeCo.
Among multiple factors influencing the occurrence of this phenomenon, the role of the exchange parameters
is poorly understood. Here, using atomistic spin simulations based on the spin Hamiltonian parameterized
through ab initio calculations for ordered stoichiometric GdFe2 and TbFe2 Laves phases C15, we investigate the
conditions for the occurrence of deterministic TIMS. Our simulations show that both inter- and intrasublattice
exchange interactions are too strong in ordered alloys and the switching is not produced for any excitation.
By varying the exchange parameters, we find their regions for which the deterministic TIMS takes place
in some interval of laser fluence. Consequently, neither weakly nor strongly antiferromagnetically coupled
materials would switch. This explains the success of disordered alloys to produce this phenomenon since the
average strength of the exchange interactions is mediated by the rare-earth-metal concentration in this case. Our
simulations also show that in the ordered lattice case only materials possessing the magnetization compensation
point are switched by this mechanism.

http://dx.doi.org/10.1103/PhysRevB.99.184401