Ab-initio spin-lattice dynamics based on the tight-binding method

Recent experiments on ultrafast demagnetization have shown that the magnetization dynamics on ultrafast timescales involves both magnetic and lattice degrees of freedom. We present a method for the quasi-classical simulation of coupled spin and lattice dynamics in metallic magnets based on a tight-binding (TB) model. The TB parameters are fitted to ab-initio data and take the structure dependence of the material into account. From the TB model we calculate both magnetic and lattice forces for the integration of the equations of motion. We use the CAHMD package [1], which implements the TB model and the atomistic spin-lattice dynamics. Our approach opens the door for a better understanding of the transfer of angular momentum between magnetization and lattice already on the electronic structure level. We demonstrate the feasibility of our method by simulations of chains and clusters.

[1] Computer code CAHMD, classical atomistic Heisenberg magnetization dynamics. A computer program package for atomistic magnetization dynamics simulations. (Danny Thonig, danny.thonig@oru.se, 2013) (unpublished, available from https://cahmd.gitlab.io/cahmdweb/)