Strong on-Chip Microwave Photon-Magnon Coupling Using Ultralow-Damping Epitaxial Y₃Fe₅O₁₂ Films at 2 K

Area of Science:

• Quantum Information Science
• Condensed Matter Physics
• Materials Science

Background:

• Yttrium iron garnet (Y₃Fe₅O₁₂ or YIG) is a leading magnetic material for magnonic quantum information science due to its exceptionally low damping.
• Developing YIG materials without rare-earth elements is crucial for scalable quantum technologies.

Purpose of the Study:

• To investigate the magnetic damping properties of epitaxial YIG thin films at low temperatures.
• To demonstrate strong coupling between magnons in YIG films and superconducting microwave resonators for hybrid quantum systems.

Main Methods:

• Epitaxial growth of YIG thin films on a diamagnetic Y₃Sc₂Ga₃O₁₂ substrate.
• Characterization of magnetic damping at 2 K.
• Fabrication of patterned YIG films and integration with a superconducting niobium (Nb) resonator.

Main Results:

• Achieved ultralow magnetic damping in YIG thin films at 2 K.
• Demonstrated strong coupling between magnons in patterned YIG films and microwave photons in a superconducting resonator for the first time.
• The YIG films contained no rare-earth elements.

Conclusions:

• Ultralow damping YIG films are promising for scalable magnonic quantum information science.
• The demonstrated strong coupling is a key step toward integrating magnonic and superconducting circuits for on-chip quantum devices.
• This work facilitates the development of hybrid quantum systems combining YIG magnons, superconducting resonators, and superconducting qubits.