Synthetic control of ultra-low loss magnons*

Magnons have promising applications in quantum information but limited material choices. Recently, vanadium tetracyanoethylene (V[TCNE]_x∼2) has been suggested as an alternative to YIG due to its room temperature ferrimagnetic order (T_N=600K), low magnetic damping (α ≈ 4 x 10^-5), and the ability to pattern and integrate micro/nanostructures. Here, we build on recent advances in our understanding of the structure-function relationships driving this behavior to achieve synthetic control of magnetization dynamics. Improvements in process control during chemical vapor deposition (CVD) thin film growth show an overall increase in saturation magnetization, M_s, as well as revealing a correlation with substrate temperature that points to an increasing crystallinity with increasing temperature. This increased control and understanding provide a foundation for further expanding the application space for V[TCNE]_x∼2-based magnonic devices and provide guidance in identifying other metal-ligand coordination compounds that may exhibit similarly exemplary magnetic properties.