Ferromagnetic resonance measurement with frequency modulation down to 2 K.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spectroscopy

Background:

• Ferromagnetic resonance (FMR) spectroscopy is crucial for understanding magnetization dynamics in thin films.
• Studying these dynamics across wide temperature, frequency, and magnetic field ranges is essential but challenging.
• Existing FMR techniques often have limitations in temperature control and simultaneous measurements.

Purpose of the Study:

• To design, fabricate, and test a novel Cryo-FMR and ISHE spectrometer.
• To enable simultaneous measurements of FMR and ISHE over an extended phase space.
• To improve FMR detection sensitivity using frequency modulation techniques.

Main Methods:

• A 2-port transmitted microwave signal measurement using a grounded co-planar waveguide.
• Frequency modulation of the input radio frequency (RF) signal.
• Integration of a sample stage within a superconducting solenoid for variable temperature (2-310 K) and magnetic field (0-±5 T).

Main Results:

• Successful demonstration of the Cryo-FMR and ISHE spectrometer's functionality.
• Characterization of Ni80Fe20 and Fe60Co20B20 thin films across a wide range of experimental parameters.
• Validation of frequency modulation for enhanced microwave absorption detection and reduced cryostat heat load.

Conclusions:

• The developed spectrometer is a powerful tool for studying magnetization dynamics and spin-related phenomena.
• The apparatus facilitates comprehensive investigations into exchange bias, spin transport, and magnon excitation.
• Simultaneous FMR and ISHE measurements open new avenues for materials characterization.