Spin-wave band gaps created by rotating square rods in two-dimensional magnonic crystals

Abstract

Absolute spin-wave band gaps can be substantially opened and tuned by rotating noncircular rods in two-dimensional magnonic crystals. Spin-wave band structures of two-dimensional magnonic crystals composed of Fe (EuO) square rods squarely arranged in a EuO (Fe) matrix are numerically calculated using the plane-wave method. The results show that it is possible to increase the width of the band gaps or to create band gaps by rotating the noncircular rods. For the system of EuO rods in Fe matrix, the largest absolute spin-wave gap in the structure of square rods is 227% of the size of that in the corresponding structure of circular rods. Such an approach may open up a new scope for engineering band gaps of two-dimensional magnonic crystals.