Perturbative Generalized Magneto-optical Ellipsometry

We present a modified method of data collection and analysis for generalized Magneto-optical ellipsometry (GME) technique. By a perturbative analysis of the light intensity (I) and Magneto-optically induced light intensity changes (δI), as functions of the incident and reflected ray polarizer axis angles (φ ₁ and φ ₂ ), we theoretically and experimentally demonstrate that in the proximity of the extinction of I condition, φ ₁ and φ ₂ can be excellently modeled by a set of quadratic and linear polynomials of φ _1,2 with R ² exceeding 0.9 999 in all cases. Compared with the previous conventional GME method (cGME), ours is at least 3.5× more time efficient, the number of adjustable parameters is reduced from 7 to up to 3, and the fitting procedure properly isolates the GME signal from nonrelated effects on I and δI functions. Moreover, the routine incorporates the minimization of the offsets of φ ₁ and φ ₂ so that the extinction of I coordinates can be determined with a precision better than 2 × 10 ^-3 deg. The reliability of our method compared with cGME is tested by measuring the complex refractive index (N) and Magneto-optical coupling constant (Q) of NiFe and Fe films and the complex Kerr angle (Φ) and the ellipsometric parameters (Ψ and Δ) on a series of ultrathin NiFe films.