Magneto-optical effect in anodized Al2O3 film with micropores electrodeposited with Co

Abstract

We have electrodeposited Co into the micropores of an anodic Al2O3 coating on Al, making Co rods of about 120 Å in diameter and 0.3–1 μm in length. The Al2O3 is amorphous, while the Co is crystalline (hexagonal form) with no preferred orientation exhibiting saturation magnetization 80% of that of bulk Co. The composite Al2O3/Co film shows prominent magnetic anisotropy perpendicular to the surface due to the shape anisotropy of the Co rods, having coercive force of ∼1.2 kOe. The Kerr rotation and the reflectivity of the films at λ=0.63 μm, Θ̂k =±15′ to ±50′, and R=5 to 15% varied from sample to sample due to interference effect of light in the films. The values of θk and R change irreversibly when heated above ∼150 °C. Stripping the Al2O3-Co film from the Al substrate by dissolving the Al, we have measured the Faraday effect and light transmittance. They increase linearly with increasing rod length, giving Θ̂f(rotation) =−0.41 deg/μm, Ψ̂f(ellipticity) =1.14 deg/μm, and α̂(absorption coefficient)=1.1 μm−1. These values conform with what is expected from the effective dielectric tensor, including off-diagonal elements, which we [Jpn. J. Appl. Phys. 23, 1580 (1984)] have formulated for composite materials containing magnetic fine particles or rods.

Oxide Films for Magneto-Optical Applications

“…The composite alumite films exhibit a prominent magnetic anisotropy perpendicualr to the film plane due to the shape anisotropy of the metal rods formed in the micropores. A composite alumite film electrodeposited with Co in the micropores exhibited fairly large Faraday rotation and ellipticity of 0.41 and 1.14 deg/~m, respectively, at A=0.63 ~m [29]. The values agreed with a theoretical calculation based on "effective dielectric tensor" [30].…”

Preparation and Faraday effect of EuS microcrystal-embedded oxide thin films

“…24 Several studies have been done concerning the magneto-optical properties of composite thin films in which microcrystalline semimagnetic semiconductors as well as metals are embedded. [25][26][27] In the case of semimagnetic semiconductor-embedded thin films, the wavelength dependence of the Faraday rotation angle manifests a blue-shift due to the quantum size effect. 27 EuS is one of the semimagnetic semiconductors, and possesses a variety of interesting magnetic properties.…”

Fabrication of ferroelectric optical nanocomposite thick films by aerosol deposition method

“…Nanocomposite systems have been prepared using various conventional method including sputtering, solgel, colloidal solutions, ion implantation, Chemical Vapor Deposition (CVD) and other hybrid methods [1][2][3][4][5][6][7]. Since these conventional methods are based on deposition of atom and cluster size with two or several kinds of element, it is very difficult that the methods may control the size and the shape of the nanomagnetic particles in the host matrix.…”