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MA: Fachverband Magnetismus

MA 9: Micromagnetism/Computational Magnetics

MA 9.5: Vortrag

Montag, 25. Februar 2008, 17:45–18:00, H 1012

three-dimensional magnetic normal modes in mesoscopic permalloy prisms — •Ming Yan, Riccardo Hertel, and Claus Michael Schneider — Institut für Festkörperforschung, IFF-9, Forschungszentrum Jülich, D-52425 Jülich

Three-dimensional (3D) magnetic normal modes in Permalloy prisms (aspect ratio 4:2:1, thickness 60-80 nm) with 3D Landau structure [1] are studied using micromagnetic finite-element simulations. Magnetic normal modes are extracted with Fourier analysis from the dynamical response of the magnetization to a weak sub-nanosecond field pulse. Among the rich excitation spectra in the range of several GHz, three well-defined types of modes are resolved: the oscillations of the asymmetric Bloch wall, of the corners, and of the 90° domain walls [2]. The modes connected with the asymmetric Bloch wall can be interpreted as the oscillations of a distorted, stretched vortex core. Instead of just one gyrotropic vortex core mode as it is known from 2D systems, multiple core modes are observed in our 3D samples. The other two types of modes, although similar to those known from 2D systems, show different characteristics consistent with the 3D character of the sample and the asymmetry of the magnetic ground state. These simulations provide precise predictions on the excitation spectra in 3D prisms and extend the knowledge of dynamic modes in confined magnetic structures from two dimensions to three. [1] R. Hertel, O. Fruchart, S. Cherifi, P.-O. Jubert, S. Heun, A. Locatelli, and J. Kirschner, Phys. Rev. B 72, 214409 (2005). [2] M. Yan, R. Hertel, C. M. Schneider, Phys. Rev. B 76, 094407 (2007).