Topological Phase Transition in One-Dimensional Magnonic Crystals Induced by Field Orientation*

Recently, it has been reported that the magnonic crystals satisfying certain conditions such as the filling fraction and the magnetic properties may have topologically non-trivial properties. Nevertheless, such parameters are not favorable candidates to realize the topological phase transition as they are not changeable in already fabricated magnonic devices. Instead, we propose orientation of the external field as a new variable to achieve the topological phase transition in the semi-infinite one-dimensional magnonic crystals. We analyzed an YIG based one-dimensional magnonic crystal polarized to an arbitrary direction by solving the Landau-Lifshitz-Gilbert equation. We compared magnon band structures and the Zak phases of magnon bands at various orientation of the bias field. For the finite structure analysis, we employed a micromagnetic modeling software to simulate the dispersion relations and the boundary modes. The result shows that the topological phase transition of the magnonic crystals can be induced by the orientation of the magnetic field and suggests new magnonic devices based on the topological properties.