Strong Photon-Magnon Coupling Using a Lithographically Defined Organic Ferrimagnet

A cavity-magnonic system composed of a superconducting microwave resonator coupled to a magnon mode hosted by the organic-based ferrimagnet vanadium tetracyanoethylene (V[TCNE]x) is demonstrated. This work is motivated by the challenge of scalably integrating a low-damping magnetic system with planar superconducting circuits. V[TCNE]x has ultra-low intrinsic damping, can be grown at low processing temperatures on arbitrary substrates, and can be patterned via electron beam lithography. The devices operate in the strong coupling regime, with a cooperativity exceeding 1000 for coupling between the Kittel mode and the resonator mode at T approximate to 0.4 K, suitable for scalable quantum circuit integration. Higher-order magnon modes are also observed with much narrower linewidths than the Kittel mode. This work paves the way for high-cooperativity hybrid quantum devices in which magnonic circuits can be designed and fabricated as easily as electrical wires. Strong coupling between superconducting microwave resonator photons and the magnons of an organic-based magnetic material is reported. The results also show that this material has ultra-low magnetic dissipation that is competitive with the best solid-state materials at low temperature. The precise integration of these two systems is promising for flexible and scalable magnonic circuit elements that operate in the quantum limit.image