Magneto-Optical Kerr Effect Driven by Spin Accumulation on Cu, Au, and Pt

The magneto-optical Kerr effect (MOKE) has recently been achieved on non-ferromagnetic metals by injecting spin currents. To use the magneto-optical Kerr effect as a quantitative tool, it is crucial to study the relationship between the Kerr rotation angle and the spin accumulation on non-ferromagnets. In this work, I measure a transient magneto-optical Kerr rotation on non-ferromagnetic metals of Cu, Au, and Pt driven by an ultrafast spin current from an adjacent ferromagnetic metal. Through comparing the measured Kerr rotation and the calculated spin accumulation, I determine the conversion ratio between the Kerr rotation and the spin accumulation to be: −4 × 10−9 (real part), −2.5 × 10−8 (real part), and −3 × 10−9 (imaginary part) rad m A−1 for Cu, Au, and Pt, respectively, at a wavelength of 784 nm.

Magneto-Optical Kerr Effect Enhancement in Co-Ti-O Nanocomposite Films

Co-Ti-O nanogranular films with different volume concentrations of a magnetic phase and Co/Ti-O layered structures with different numbers of layer pairs are studied by the magneto-optical Kerr effect. It is shown that, unlike the case of homogeneous metal films, the magneto-optical spectra of the nanogranular films exhibit resonance with a significant increase in the Kerr rotation angle in the wavelength range 500-700 nm. It is found that the Kerr rotation angle of the Co/Ti-O layer structures in the wavelength range 500-600 nm grows by an order of magnitude as compared to its value for ordinary Co films.

Magneto-Optical Properties of Multilayered FePt for High Density Recording

ABSTRACTThe Si3N4/FePt/Si3N4/Al/Si structures have been fabricated. 57 nm silicon nitride films have been used as dielectric layer for heat dissipation and 500 nm Al film used for reflection layer. The Kerr rotation angle was changed with the FePt layer thickness. At the 65 % Pt composition in 10 nm FePt layer, the maximum Kerr rotation angle was 0.82°. As increase with FePt thickness the Kerr angle is slightly decreased. The change of Kerr rotation angle and the thermal behavior of multilayered structure according to FePt thickness variation were also calculated by computer simulation.

FARADAY AND MAGNETIC KERR ROTATION MEASUREMENTS ON Co AND Ni FILMS AROUND M2,3 EDGES

Faraday and longitudinal magnetic Kerr rotation measurements were performed on Co and Ni single layer films around their M2,3 edges, at room temperature under an applied magnetic field of 0.82 T generated by a magnetic circuit composed of permanent magnets. The longitudinal Kerr rotation angle spectra are in good agreement with those calculated from the Faraday rotation spectra in Ni but different in Co. The main reason for the difference in Co was explained with the difference of the magnetization between a longitudinal Kerr (saturated) and a Faraday (unsaturated) configuration under the magnetic field of 0.82 T. This was supported by the calculated result from magnetic circular dichroism (1.2 T, 140 K) measurement on Co.

THEORY OF OPTICAL AND MAGNETOOPTICAL PROPERTIES OF INVAR COMPOUNDS

The frequency-dependent optical conductivity tensor for ferromagnetic transition metal compounds is determined in a theoretical framework, in which spin-orbit interaction and ferromagnetic exchange interaction are included on an equal footing. The interplay of the latter two mechanisms manifests itself in substantial modifications of the diagonal tensor components and the appearance of offdiagonal components, and thereby in optical and magnetooptical properties. Numerical calculations for Fe3Pt using a “high-spin” model yield a polar Kerr rotation angle in good agreement with experimental data, Results for the diagonal tensor components reveal very pronounced differences between assumed ”high-spin” and ”low-spin” models of Fe3Pt. We conclude that specific experimental studies should be able to provide more information on the still not completely resolved issue of the nature of the INVAR mechanism in Fe3Pt.