Iron garnet thin films for spintronic and photonic devices

Caroline A. Ross, Massachusetts Institute of Technology

Ferromagnetic insulator thin films provide unique functionality in spintronic, magnonic, and magnetooptical devices. Yttrium iron garnet has very low magnetic damping, and substitution of rare earth ions as well as the introduction of point defects such as antisite defects allows the anisotropy, magnetostriction, compensation temperature and optical properties to be tuned. We use pulsed laser deposition to produce single crystal films of rare earth garnets down to a thickness of 2.5 nm, about 2 unit cells. We show intriguing magnetic behavior in garnet/heavy metal bilayers including spin orbit torque-driven domain wall motion at room temperature at velocities exceeding 4 km/s, switching the magnetic state. Iron garnets also exhibit magnetooptical activity and high transparency in the infrared, and we show how garnets grown on silicon can be used in integrated magnetooptical isolators to control the flow of light in photonic circuits.

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