Low-Damping Ferromagnetic Resonance in Electron-Beam Patterned, High-$Q$ Vanadium Tetracyanoethylene Magnon Cavities

Abstract

Integrating patterned, low-loss magnetic materials into microwave devices and circuits presents many challenges due to the specific conditions that are required to grow ferrite materials, driving the need for flip-chip and other indirect fabrication techniques. The low-loss ($\alpha =3.98\pm 0.22\times 10^{-5}$), room-temperature ferrimagnetic coordination compound vanadium tetracyanoethylene (${\mathrm{V}[\mathrm{TCNE}]}_x$) is a promising new material for these applications that is potentially compatible with semiconductor processing. Here we present the deposition, patterning, and characterization of ${\mathrm{V}[\mathrm{TCNE}]}_x$ thin films with lateral dimensions ranging from 1 micron to several millimeters. We employ electron-beam lithography and liftoff using an aluminum encapsulated poly(methyl methacrylate), poly(methyl methacrylate-methacrylic acid) copolymer bilayer (PMMA/P(MMA-MAA)) on sapphire and silicon. This process can be trivially extended to other common semiconductor substrates. Films patterned via this method maintain low-loss characteristics down to 25 microns with only a factor of 2 increase down to 5 microns. A rich structure of thickness and radially confined spin-wave modes reveals the quality of the patterned films. Further fitting, simulation, and analytic analysis provides an exchange stiffness, $A_{ex}=2.2\pm 0.5\times 10^{-10}$ erg/cm, as well as insights into the mode character and surface spin pinning. Below a micron, the deposition is non-conformal, which leads to interesting and potentially useful changes in morphology. This work establishes the versatility of ${\mathrm{V}[\mathrm{TCNE}]}_x$ for applications requiring highly coherent magnetic excitations ranging from microwave communication to quantum information.

18 pages, 7 figures, submitted to APL Materials

References in corpus (5)

• Strongly coupled magnons and cavity microwave photons
• Realization of XNOR and NAND spin-wave logic gates
• Spin waves in micro-structured yttrium iron garnet nanometer-thick films
• Low loss spin wave resonances in organic-based ferrimagnet vanadium tetracyanoethylene thin films
• Ultra-low damping in lift-off structured yttrium iron garnet thin films

Cited by in corpus (5)

• Hybrid magnonics: physics, circuits and applications for coherent information processing
• Magnon-photon strong coupling for tunable microwave circulators
• A Magnon Scattering Platform
• Predicted strong coupling of solid-state spins via a single magnon mode
• Exploring a quantum-information-relevant magnonic material: Ultralow damping at low temperature in the organic ferrimagnet V[TCNE]x