Temperature Evolution of Magnetic Resonance Spectra in Metal-Insulator Nanogranular Composites with Paramagnetic Ions in an Insulating Matrix

Films of metal-insulator nanogranular (CoFeB)(x)(LiNbO3)(100 -) (x) and (CoFeB)(x)(Al2O3)(100 -) (x) composites with different content x of a ferromagnetic metallic phase have been investigated by the magnetic resonance method in a wide temperature range (4.2-360 K). The systems under study are characterized by a high concentration of paramagnetic Fe and Co ions, which are dispersed in the insulating medium between ferromagnetic CoFeB granules. The experimental spectra of these systems show a peak of ferromagnetic resonance associated with the ferromagnetic granule array and an additional less intense absorption peak associated with the electron paramagnetic resonance of Fe3+ ions in the insulating matrix. It has been found that the position and intensity of this peak depend on the composition of the system and temperature. The observed behavior is explained by existence of exchange interaction between magnetic ions and ferromagnetic granules.

Automated summary

The magnetic resonance spectra of metal-insulator nanogranular composites were investigated and showed a ferromagnetic resonance peak associated with ferromagnetic granules and an electron paramagnetic resonance peak associated with Fe3+ ions in the insulating matrix. The position and intensity of the peaks depended on the composition and temperature.