Loic Temdie Kom Thesis defense

Abstract : This thesis focuses on the design of non-reciprocal magnonic devices, such as isolators and circulators, at the micrometer scale. To achieve this, we conducted an experimental study using spectroscopy to investigate the propagation properties of high-k spin waves in thin YIG films. We present several approaches for shaping unidirectional micrometer-scale beams across a broad frequency range, using low applied magnetic fields. The first approach involves using magnetic nanowires arrays made from permalloy and cobalt, with wavelengths reaching up to 70 nm. However, spectroscopic analysis reveals significant challenges in characterizing the propagation properties of high-k spin waves. This work also introduces a technique for the unidirectional excitation of high-k spin waves, with wavevectors reaching up to 50 rad/μm, using gold nanowire arrays. Complex variations in amplitude as a function of propagation distance were observed for highk spin waves across different geometries.
These effects are attributed to artifacts resulting from both design limitations and the constraints of nanofabrication. These findings emphasize the importance of further investigation into the resonant coupling mechanisms between nanostructures and spin waves, as well as the electrical characterization of high-k spin waves.