Magneto-optical properties of nanocomposites ferromagnetic-carbon

•Magneto-optical properties of ferromagnetic metal-carbon nanocomposites are presented.•TKE spectral shapes depend on granule compounds.•CoC system shows a transition from amorphous granules to crystalline Co granules.•CoFeB-C TKE spectra weakly depend on FM-granule concentration.•MO features are related to possibility of chemical reactions between C with Co and B. Current work is devoted to the study of magneto-optical properties of ferromagnetic metal-carbon nanocomposites that belong to a new class of composites in which partial mixing and the formation of metastable phases between components are allowed. Films of nanocomposites were obtained using ion-beam sputtering of composite target on ceramic substrates. There were three systems synthesized with wide range of magnetic phase concentrations – (Co40Fe40B20)X(SiO2)100−X(1), (Co401Fe40B20)X(C)100−X(2)and (Co)X(C)100−X (3). It is found that the evolution of the TKE spectra for the [(Co)x (C)100−x] system with a change in the concentration of FM granules indicates a transition from amorphous CoC granules to crystalline Co granules in a carbon matrix. The shape TKE spectra for the system2 was weakly dependent on the concentrations x. The difference in the behavior of the magneto-optical properties of the [(Co)x (C)100−x] and [(Co40Fe40B20)x(C)100−x] system is explained on the basis of the composite formation model, taking into account the possibility of chemical reactions of carbon with metals and boron.