Magnetic circular dichroism of Co nanoparticles localized in matrices of various types

Particles–Matrix Bond in ZnCoO:H and ZnCoAlO:H Films: Issues of Magnetism and Spin Injection

“…Though the X-ray diffraction patterns obtained for the films exhibited diffraction peaks corresponding only to the ZnO crystal [ 23 , 24 ], the element-selective XANES spectroscopy at the Co K-edge confirmed the presence of metallic cobalt in the CZO:20 and CZO:30 films. In combination with XRFA data, the relative content of metallic cobalt in the films was estimated as 7.6% and 13%, respectively [ 29 ]. The rest of the samples were not examined with XANES.…”

“…The average size of the included Co particles (<D>) was estimated by the Bean–Livingston formula T b = K eff (4πr 3 /3)/25 k B [ 30 ], where K eff is the energy of the effective magneto-crystalline anisotropy (4.3 × 10 5 J/m 3 [ 29 , 31 ]), k B is Boltzmann’s constant, and r is the particles radius. The <D> values for the studied samples are shown in the Table 2 .…”

“…At the same time, in each pair of the samples, the MCD signal of CAZO:H is noticeably higher. It was also shown that the contributions of metallic Co particles and the ZnO:Co 2+ matrix dominate in different regions of the MCD spectrum [ 29 ]. Moreover, it was found that with an increase in the filling density of the particles, the MCD signal increases.…”

“…It was traced that the I Co value for the CAZO:20 film is 1.85 times greater than the I Co value for the CZO:20 sample. According to XANES data [ 29 ], the relative content of metallic cobalt in the CZO:20 film is 7.6%. Consequently, this indicator should increase by 1.85 and reach ~14% for the CAZO:20 film.…”

“…The MCD spectrum of the CAZO:20 film is close to that of the CZO:30 film ( Figure 5 ). According to XANES data [ 29 ], the relative content of metallic cobalt in a CZO:30 film is 13%. It is noteworthy that the values of I Co and I ZnO for the CAZO:50 film are 2.7 times higher than for the CZO:50 film.…”