Interference of coherent spin waves in micron-sized ferromagnetic waveguides

TL;DR

This paper experimentally investigates how coherent spin waves interfere in micron-sized ferromagnetic waveguides, revealing the transition from propagating to standing wave patterns using Brillouin light scattering microscopy.

Contribution

It provides the first detailed experimental visualization of spin-wave interference patterns and phase transitions in micron-scale ferromagnetic waveguides.

Findings

Interference patterns depend on waveguide eigenmodes with different wavevectors.

Phase transition from propagating to standing waves observed.

Brillouin light scattering microscopy effectively maps local spin-wave intensity and phase.

Abstract

We present experimental observations of the interference of spin-wave modes propagating in opposite directions in micron-sized NiFe-waveguides. To monitor the local spin-wave intensity distribution and phase of the formed interference pattern, we use Brillouin light scattering microscopy. The two-dimensional spin-wave intensity map can be understood by considering the interference of several waveguide eigenmodes with different wavevectors quantized across the width of the stripe. The phase shows a transition from linear dependence on the space coordinate near the antennas characteristic for propagating waves to discrete values in the center region characteristic for standing waves.