Spin-wave Confinement and Coupling in Organic-Based Magnetic Nanostructures*

We present the synthesis of a new class of organic-based magnetic nanostructures consisting of nanowires of V[TCNE]_x that assemble along the ridges of a grooved substrate. These nanowires exhibit uniaxial magnetic anisotropy in direct contrast to the isotropic in-plane response of typical thin-films. When different magnon modes excited in these structures are brought into resonance by varying the orientation of an in-plane magnetic field, we observe anticrossing behavior, indicating strong coherent coupling between excitations. Furthermore, micromagnetic simulations using real nanowire profiles extracted from cross-sectional scanning electron microscopy faithfully reproduce the experimentally measured spectra without any free parameters, including spin-wave and other higher-order modes. These results introduce a new degree of freedom for organic-based magnetism and spintronics, and together with recent demonstration of encapsulation technologies and demonstrated functional microwave devices that exhibit high quality factors across a frequency range, suggest future promising applications in microwave electronics and quantum magnonics.