Regensburg 2013 – scientific programme

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MA: Fachverband Magnetismus

MA 43: Magnetization Dynamics II of 3

MA 43.8: Talk

Thursday, March 14, 2013, 16:45–17:00, H22

Spin-lattice dynamics under conservation of angular momentum — •Matthias Assmann and Ulrich Nowak — University Konstanz, 78457 Konstanz, Germany

On ultrafast time scales conservation laws can enforce strong constraints onto the magnetization dynamics. These restrictions cannot be described by the Landau-Lifshitz-Gilbert equation with its dissipative dynamics. In this talk a set of coupled microscopic equations of motion for the spin and lattice dynamics is proposed, which include a direct coupling between spins and lattice, so that energy and angular momentum can be transferred between these subsystems. For the coupling between lattice and spin degrees of freedom a two-site anisotropy arising from spin-orbit coupling is considered as well as magnetic dipole-dipole interaction. Both of these coupling terms allow for a dynamics, which obey all conservation laws, including the conservation of total angular momentum. For the numerical treatment in our simulations new sympletic algorithms are used. As a test the Einstein-De Haas effect is reproduced as well as the Barnett effect. Furthermore, heat dissipation from the magnetic subsystem into the lattice is investigated in film geometries.