Ferromagnetic resonance: Electrical detection vs conventional absorption measurements

Ferromagnetic resonance (FMR) in point contacts to a soft CoSiBFeNb magnet is examined by three different techniques: electrical detection via rectification, power-absorption measurements, and time-resolved measurements of magnetization dynamics. The electrical detection is realized by taking advantage of the point contact as a nano-scale bolometer which monitors the microwave current absorbed by the sample. The power-absorption measurements exploit an external sensor to monitor the microwave absorption as a function of applied magnetic field. Finally, a high-bandwidth sampling oscilloscope allows for the time-resolved measurement of magnetization dynamics during FMR and provides the phase-and amplitude-characterization of FMR at 4-8 GHz. Simultaneous detection of the rectification signal, microwave absorption, and time-resolved microwaves allows for a direct comparison of the electrical detection and conventional FMR schemes. A good agreement between different FMR methods was found and the expected phase shift and amplitude variation for a driven resonance were confirmed. (C) 2014 AIP Publishing LLC.