Magnetooptical properties and FMR in granular nanocomposites (Co84Nb14Ta2)x(SiO2)100−x

Abstract

For nanodimensional magnetically inhomogeneous amorphous granular films of the system (Co 84 Nb 14 Ta 2 ) x (SiO 2 ) 100−x , 30 ≤ x ≤ 60 at.% the concentration dependences of the magnetooptical Kerr effect (MOKE) spectra and FMR have been investigated. The observed changes in the MOKE and FMR spectra are associated with transformations of microstructure and topology of the nanocomposites. For the compositions within the percolation region the transversal Kerr effect increases by an order of magnitude.

Magnetooptical Properties of Layer-by-Layer Deposited Ferromagnet—Dielectric Nanocomposites

“…Evolution of the TKE magnetic field dependence with increase of the FM phase content is also similar in all the systems studied [14,15]. As example in Figure 2 are shown the TKE magnetic field dependence of a series of nanocomposites (Co 86 Nb 12 Ta 2 ) Z (SiO 2 ) 100−Z , measured at hν = 1.42 eV (normalized).…”

“…The effect magnitude essentially depends on chemical composition of the granules. Maximum magnitudes of MO response are achieved in the systems with Zr as amorphizator, at Z = 47 at%, in the system with Boron content at Z = 58 at% and in the system with niobium and tantalum at Z = 46 at% [15]. Concentration position of the maximum is determined by geometrical particularities of the composites, which are near percolation threshold-minimal thickness of the dielectric barrier, through which the tunneling of polarized electrons is going between the FM granules.…”

“…Studies of MO properties of amorphous metal-dielectric bulk nanocomposites have shown that changes of MO properties in all our systems with increasing concentration proceed virtually identically [14,15]. The TKE spectra of nanocomposites of all systems demonstrate similar frequency dependencies, varying only in details, namely by magnitude of the effect, as well as position of maximums and zero points of the effect example of spectra of nanocomposite (Co 86 Nb 12 Ta 2 ) Z (SiO 2 ) 100−Z in the wide concentration range, В-spectra of nanocomposites with different compositions, the FM phase concentration being near the percolation threshold).…”

“…First a brief description of MO properties of bulk nanocomposites. Studies of MO properties of bulk nanocomposites with various chemical compositions, both ferromagnetic granules (Co 84 Nb 14 Ta 2 , Co 40 Fe 40 B 20 , Co 45 -Fe 45 Zr 10 , Со, FePt), and a dielectric matrix (SiO 2 , Al 2 O 3 LiNbO) [14][15][16][17] have shown that MO spectra substan-tially differ from witnesses' spectra, FM alloys and Co. The TKE spectra demonstrate a strong nonmonotonous dependence on the metallic volume fraction with a crossover at the percolation threshold.…”

Special features of the ferromagnetic resonance in cobalt-containing granulated nanostructures

“…Qualitatively similar dependence was observed in [10] for the Co-Cu nanogranulated system. Values of х th were in the range 40-45 at.% for the examined structures and correlated with the concentration of the metal phase at which the maximum changes of the Kerr equatorial effect and maximum giant reluctance values were observed [11]. In the same region, the temperature dependences of the electric resistance changed [5].…”