We describe a new type of ferromagnetic resonance (FMR) spectroscopy that is based on a calorimeter sensor. We use an atomic force microscopy cantilever coated with a ferromagnetic thin film as a bimaterial sensor to measure absorption of microwaves at 9.17 GHz. The spectra show a peak in the cantilever deflection as a function of applied magnetic field corresponding to a peak in the absorbed microwave power that occurs at the FMR resonance of the ferromagnetic film. The saturation magnetization M3ff and the damping factor α were determined from the FMR microwave absorption spectra for Co, NiFe, and Ni thin films. The data correlate well with conventional FMR spectra taken with a tuned cavity spectrometer. Our instrument can detect magnetic moments as small as 1.3 c 10-12 A m2 (1.3X10-9 emu) with prospects for snesitivity improvements to the 1 x 10u-16^ Am2 (1X10-12emu) level. The technique provides a potentially superior way to make quantitative measurements of saturation magnetization of thin-film samples with very small total magnetic moments.
Citation: Review of Scientific Instruments
Pub Type: Journals
atomic force microscopy, bimetallic thermal sensor, ferromagnetic resonance, magnetic moments, thermal absorption, thin-film samples