On-Chip Detection of Magnetic Dynamics for Single Microscopic Magnetic Dot

An inductive-based detection method of ferromagnetic resonance spectrum is demonstrated. For a single microscopic (~40 nm × 40 μm × 60 μm) magnetic dot, which is much smaller than the microwave wavelength, the change in the microwave transmission signal is as large as 15 dB when its magnetic permeability changes. This detection is several orders more sensitive than the conventional transmission line method. Further understanding and development of this concept may lead to a microscopic microwave permeability sensor.