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MA: Fachverband Magnetismus

MA 47: Micro- and Nanostructured Magnetic Materials II

MA 47.2: Vortrag

Donnerstag, 29. März 2012, 17:30–17:45, EB 202

Energy Landscapes and magnetization dynamics of nanostructured magnetic materials — •David Gallina, Peter Jensen, and Gustavo M. Pastor — Institut für Theoretische Physik, Universität Kassel, 34132 Kassel, Germany

The magnetic relaxation processes in disordered two-dimensional ensembles of dipole-coupled magnetic nanoparticles are theoretically investigated. The energy landscape of the system is explored numerically by calculating saddle points, adjacent local minima and the associated minimum energy paths (MEPs) as functions of the structural disorder and external magnetic field. Representative MEPs between fully-polarized states having opposite magnetization directions M^→ and −M^→ are illustrated. The changes in energy and magnetization along the reaction coordinate are discussed. A connected (ergodic) network of the thermodynamic-relevant low-energy local minima and the corresponding transition rates between them are determined. As a result, we follow the time evolution of the system for different initial configurations and manipulations of the external magnetic field in order to simulate different experiments on these magnetic systems.