Thickness dependence of linear and quadratic magneto-optical Kerr effects in ultrathin Fe(001) films

Abstract

Magneto-optical ͑MO͒ Kerr effect ͑MOKE͒ magnetometry is one of the most widely employed techniques for the characterization of ferromagnetic thin-film samples. Some information, such as the magnitude of coercive fields or anisotropy strengths, can be readily obtained without any knowledge of the optical and MO properties of the material. On the other hand, a quantitative analysis, which requires precise knowledge of the material's index of refraction n and the MO-coupling constants K and G, is often desirable, for instance, for the comparison of samples which are different with respect to ferromagnetic layer thicknesses, substrates, or capping layers. While the values of the parameters n and the linear MO-coupling parameter K reported by different authors usually vary considerably, the relevant quadratic MO-coupling parameters G even for Fe are completely unknown. Here, we report on measurements of the thickness dependence ͑0-60 nm͒ of the linear and quadratic magneto-optical effects in epitaxial bcc-Fe͑001͒ wedge-type samples performed at a commonly used laser wavelength of 670 nm. By fitting the thickness dependence we are able to extract a complete set of parameters n, K, ͑G 11 − G 12 ͒, and G 44 for the quantitative description of the MOKE response of bcc-Fe͑001͒. We find the parameters n, K, and G to significantly differ for films thinner than about 10 nm as compared to those for thicker films, which is indicative of a thickness dependence of the electronic properties or of surface contributions to the MOKE. The magnitude of the quadratic magneto-optical effect is found to be about one-third of the record values reported recently for Co 2 FeSi.

Systematic study of magnetic linear dichroism and birefringence in (Ga,Mn)As

“…The Voigt effect is even in M while the Faraday and Kerr effects are odd in M. There is no broadly accepted term for the quadratic (even-in-M) magneto-optical effect in the reflection at normal incidence with in-plane M, although sometimes it is called quadratic magneto-optical Kerr effect (QMOKE) [23], Hubert-Schäfer effect [24], orientational magneto-optical effect [28,29], or it is included in the "reflection analogy to the Voigt effect" [30]. We will adopt here the last terminology.…”

Magneto-optical investigation of epitaxial nonstoichiometric Co2MnGe thin films

“…35 The microscopic details leading to the observation of QMOKE in a given sample are not yet firmly established, but QMOKE has been observed in a range of cobalt-based Heuslercompound thin films such as Co x Mn y Ge 1−x−y ͑111͒, 36,37 Co 2 FeSi͑001͒, 20,21 Co 2 MnSi͑001͒, 19 and ͑among other systems͒ thin Fe films. 30,31,38,39 To quantify the amplitude of the QMOKE component, we have carried out the "eight field method" ͑see Sec. II and Refs.…”

Photonic spin Hall effect in topological insulators

“…The Kerr effect can be used for determining the surface sensitivity of material, studying magnetic materials on account of its robustness and so on [32]. Here we investigate the Kerr rotation angles changing with different axion coupling under the condition of external magnetic field.…”