The role of the internal demagnetizing field in a surface-modulated magnonic crystal

Abstract

Magnonic crystals with locally alternating properties and specific periodicities exhibit interesting effects, such as a multitude of different spin-wave states and large band gaps. This work aims for demonstrating and understanding the key role of local demagnetizing fields in such systems. To achieve this, hybrid structures are investigated consisting of a continuous thin film with a stripe modulation on top favorable due to the adjustability of the magnonic effects with the modulation size. For a direct access to the spin dynamics, a magnonic crystal was reconstructed from `bottom-up', i.e., the structural shape as well as the internal field landscape of the structure were experimentally obtained on the nanoscale using electron holography. Subsequently, both properties were utilized to perform dynamic response calculations. The simulations yield the frequency-field dependence as well as the angular dependence of spin waves in a magnonic crystal and reveal the governing role of the internal field landscape around the backward-volume geometry. The complex angle-dependent spin-wave behavior is described for a 360 degree in-plane rotation of an external field by connecting the internal field landscape with the individual spin-wave localization.

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• Driving magnetization dynamics in an on-demand magnonic crystal by magneto-elastic interaction
• Graded index lenses for spin wave steering
• Non-uniform spin wave softening in 2D magnonic crystals as a tool for opening omnidirectional magnonic band gaps
• Symmetry and localization properties of defect modes in magnonic superlattices
• Reversible tuning of omnidirectional band gaps in two-dimensional magnonic crystals by magnetic field and in-plane squeezing
• Spin-wave Confinement and Coupling in Organic-Based Magnetic Nanostructures
• Transition magnon modes in thin ferromagnetic nanogratings