Time-gating of coherent spin-wave echoes from edge reflections in micro-patterned YIG

Raw data and Python code for the manuscript "Time-gating of coherent spin-wave echoes from edge reflections in micro-patterned YIG". All data files and source code are provided. The ipynb file is a python jupyter notebook file which works when all the data files are in the same folder. The notebook file contains all the source codes to generate all the figures. Abstract: The extraction of intrinsic spin-wave damping and group velocity in a micro-structured yttrium iron garnet (YIG) device from direct transmission signals can be complicated by near-field inductive and capacitive coupling from closely spaced coplanar waveguide (CPW) antennas. In this work, we investigate a micron-sized YIG device and observe MHz-scale spectral ripples in its continuous-wave transmission spectra whose periodicity disperses with the applied magnetic field. We demonstrate that by performing time-domain transformations of broadband \(S\)-parameters, these ripples can be explicitly decoded as coherent spin-wave echoes originating from edge reflections. Because the echo wave-packet travels a significantly longer path than the direct signal, it effectively decouples from the CPW near-field feedthrough, stabilizing into a propagating magnon mode. Without the need for additional probes, we extract a relaxation time of \(\tau \approx 50~\mathrm{ns}\) and an effective Gilbert damping constant of \(\alpha_{\mathrm{exp}} \approx 8 \times 10^{-4}\), while directly resolving group velocities that agree well with theoretical predictions where direct short-distance measurements deviate. Furthermore, reflection spectroscopy independently supports the origin of these signals. These observations are further corroborated by micromagnetic simulations. Our work establishes a robust protocol for magnon-based metrology, demonstrating how boundary effects can be utilized for on-chip delay elements.