2015/07/31 by Mohammad Sayad, Michael Potthoff · 39 citations
Physics and Astronomy · #Dynamics (music) #Electron #Exchange interaction #Ground state #Magnetic field #Perturbation theory (quantum mechanics) #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Rare-earth and actinide compounds #Relaxation (psychology) #Spin (aerodynamics) #Spin wave #cond-mat.mes-hall #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1088/1367-2630/17/11/113058
published in New Journal of Physics 17(11), 113058 (IOP Publishing) · 15 pages, 13 figures, v2 with minor changes
openalex publication_date 2015/11/27 · arxiv created 2015/11/28 · arxiv updated 2015/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The real-time dynamics of a classical spin in an external magnetic field and local exchange coupled to an extended one-dimensional system of non-interacting conduction electrons is studied numerically.Retardation effects in the coupled electron-spin dynamics are shown to be the source for the relaxation of the spin in the magnetic field.Total energy and spin is conserved in the non-adiabatic process.Approaching the new local ground state is therefore accompanied by the emission of dispersive wave packets of excitations carrying energy and spin and propagating through the lattice with Fermi velocity.While the spin dynamics in the regime of strong exchange coupling J is rather complex and governed by an emergent new time scale, the motion of the spin for weak J is regular and qualitatively well described by the Landau-Lifschitz-Gilbert (LLG) equation.Quantitatively, however, the full quantum-classical hybrid dynamics differs from the LLG approach.This is understood as a breakdown of weak-coupling perturbation theory in J in the course of time.Furthermore, it is shown that the concept of the Gilbert damping parameter is ill-defined for the case of a one-dimensional system.