Magnon polaritons in a van der Waals ferromagnet coupled to a superconducting resonator
Alvaro Bermejillo-Seco, Luuk J. van der Goot, Matteo Arfini, Yaroslav M. Blanter, Gary A. Steele + 1 more
TLDR
Researchers achieved magnon-photon hybridization in a 2D van der Waals ferromagnet using a superconducting resonator, paving the way for integrated quantum circuits.
Key contributions
- Observed magnon-photon hybridization in exfoliated flakes of 2D vdW ferromagnet Cr$_2$Ge$_2$Te$_6$ (down to 30 nm).
- Utilized a low-impedance superconducting resonator to enable strong coupling and magnon polariton formation.
- Evidenced hybrid excitations through reproducible avoided crossings across six different devices.
- Demonstrated coupling strength scales with thickness, indicating monolayer hybridization is within reach.
Why it matters
This work overcomes a major challenge in integrating magnetic excitations with superconducting circuits by demonstrating magnon-photon hybridization in 2D materials. It opens new avenues for developing compact, tunable quantum devices and exploring fundamental physics in low-dimensional magnetic systems. The potential for monolayer hybridization is particularly exciting for future quantum technologies.
Original Abstract
Achieving magnon-photon hybridization in the microwave regime is essential for integrating magnetic excitations with superconducting circuits. While this has been extensively demonstrated in bulk magnetic systems, realizing it in two-dimensional van der Waals materials remains challenging due to their reduced magnetic volume and increased dissipation. Here, magnon-photon hybridization is observed in exfoliated flakes of the van der Waals ferromagnet Cr$_2$Ge$_2$Te$_6$, with thicknesses down to 30 nm. The resulting magnon polaritons-hybrid excitations of cavity photons and magnons-are evidenced by reproducible avoided crossings across six devices, enabled by a low-impedance superconducting resonator design. The coupling strength follows the expected square-root dependence on thickness, and extrapolation of this scaling indicates that hybridization in the monolayer limit is within reach.
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