Ferrimagnetic resonance in thin film organic-based magnets*

Recent advances in spintronics suggest that the high frequency response of ferromagnetic materials is an attractive path to generating pure spin currents. Further, experiments in inorganic systems indicate that the linewidth of the ferromagnetic resonance (FMR) is an important metric for FMR driven spin injection. Here we perform magnetic resonance measurements on the organic-based ferrimagnetic semiconductor V[TCNE]$_{\mathrm{x\sim 2}}$, consisting of vanadium ions in a network of organic linking molecules. We observe a single resonance with an extremely sharp linewidth, on the order of 1 Oe (yttrium iron garnet, YIG, has a comparable linewidth). Previous studies of V[TCNE]$_{\mathrm{x\sim 2}}$ show similar linewidths but with many peaks in the spectrum, indicating that our results represent a significant improvement in sample homogeneity. Finally, we also demonstrate the ability to manipulate the magnetic properties through chemical modification of the organic linker, yielding thin films of V[MeTCEC] and V[EtTCEC]. These studies demonstrate the potential for high frequency all-organic spintronic and magnetoelectronic devices.