title: Comparison of quantum and classical relaxation in spin dynamics.
abstract: The classical Landau-Lifshitz equation with a damping term has been derived from the time evolution of a quantum mechanical wave function under the assumption of a non-Hermitian Hamilton operator. Further, the trajectory of a classical spin (S) has been compared with the expectation value of the spin operator (Ŝ). A good agreement between classical and quantum mechanical trajectories can be found for Hamiltonians linear in Ŝ or S, respectively. Quadratic or higher order terms in the Hamiltonian result in a disagreement.
authors.affiliation: Institut für Angewandte Physik, Universität Hamburg, D-20355 Hamburg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Wieser