The exploration of coherent magnonics relies implicitly on the ability to excite and exploit long lived spin wave excitations in a magnetic material. That requirement has led to the nearly universal reliance on yittrium iron garnet (YIG), which for half a century has reigned as the unchallenged leader in high-Q, low loss magnetic resonance and spin wave excitation despite extensive efforts to identify alternative materials. Recent work has identified the organic-based ferrimagnet vanadium tetracyanoethylene (V[TCNE]2) as the first credible alternative to YIG. In contrast to other organic-based materials V[TCNE]2 exhibits a Curie temperature of over 600 K with robust room temperature hysteresis with sharp switching to full saturation. Further, since V[TCNE]2 is grown via chemical vapor deposition (CVD) at 50 C it can be conformally deposited as a thing film on a wide variety of substrates. However, despite the high level of synthetic reproducibility, as recently evidenced by direct integration into functional microwave magnonic devices, the fundamental structure-property relationships giving rise to these remarkable magnetic properties are still not fully understood. Here, we will discuss the measurement of coherent magnonic excitations in patterned micro- and nano-structure that maintain high quality magnetic resonance (Q ~ 2,000 - 8,000) and provide important insights into the origin of magnetic ordering in V[TCNE]2 and related materials. These high-Q resonances reveal the crystal-field driven magnetic anisotropy of the nanostructures, providing clues as to the underlying structural order and revealing shape-tuned strong coupling between individual quantum-confined modes.

Vanadium tetracyanoethylene for coherent magnonics

2019 Spring National Meeting

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