Dynamic simulation of the quasiparticle excitations spectra in the magnetic bcc iron

Abstract

Abstract We used the LAMMPS algorithm for spin-lattice dynamics to model the coupled relaxation processes of the spin and lattice subsystems in bcc Fe with the aim to investigate the relevant phonon and magnon dispersion laws at T = 300 K. The atomic interactions were modeled via the semi-empirical many-body Chamati EAM potential, while the distance-dependent spin coupling relied on the Heisenberg-type Hamiltonian. In the state of mutual equilibrium of the spin and lattice ensembles, we have calculated the dynamic matrix of the phonons, the intermediate scattering function, the dynamical structure factor and finally the phonon spectra in bcc-iron. We found that the experimental data could be described best by the elastic [100] and [110] modes calculated in the dynamic structure factor approach for all wavevector absolute values q. Moreover, the impact of magnons on the phonon spectra is pronounced for all investigated directions, but there are elastic vibrations which remain unaltered by interaction with magnons.