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MA: Fachverband Magnetismus
MA 59: Posters Magnetism III
MA 59.22: Poster
Freitag, 20. März 2020, 09:00–12:00, P2/EG
Lifetimes of large magnetic structures — •Moritz Sallermann1,2, Stefan Blügel1, and Hannes Jónsson2 — 1Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany — 2Science Institute and Faculty of Physical Sciences, University of Iceland, VR-III, 107 Reykjavík, Iceland
The thermal stability of certain spin configurations is of tremendous importance in the design of experimental setups and spintronics devices. In the framework of harmonic transition state theory, this critical property can be estimated. Such a calculation produces the rate of a specific reaction, following a known transition path from the initial configuration to a final state. The reaction rate is determined from local properties of the energy landscape around two designated points along the transition path - the initial state and the saddle point.
Specifically it is required to know the ratio between the determinant of the Hessian matrix at the initial and at the saddle point configuration, which is linked to the entropic bottleneck of the reaction.
As one considers large systems, however, the straightforward approach of computing all eigenvalues of the Hessian, turns out to be much too computationally expensive and therefore not feasible. We explore an alternative avenue of obtaining the transition rate via statistically estimating the entropic contribution, thus avoiding the expensive eigenvalue decompositions. We apply this approach to lifetime estimations for large magnetic structures, modelled as classical atomistic spins with an extended Heisenberg Hamiltonian.