Magneto-optical Kerr spectroscopy of (Ga,Mn)(As,P) ferromagnetic layers: Experiments and k.p theory

Abstract

We present a theoretical and experimental study of the magneto-optical properties of thin (Ga,Mn) (As,P) layers on GaAs substrates with varying phosphorus fractions. Using a 40-band k.p model as well as an antiferromagnetic (s, p)-d exchange interaction, we calculate the dielectric tensor, the Kerr rotation angle, and the ellipticity in the interband transition region. Our calculations are validated through a set of accurate comparisons with experimental results. The Kerr ellipticity peak is found to be 2 to 3 times larger than the Kerr rotation angle both experimentally and theoretically. This work will enable to optimize the magneto-optical effects in these layers for maximum sensitivity in ultra-fast magnetization dynamics and domain microscopy experiments. Published by AIP Publishing.

Magneto-optical Kerr spectroscopy in ferromagnetic semiconductors: determination of the intrinsic complex magneto-optical Voigt constant

“…Previous theoretical works on GaAs 1−x P x layers has been shown that the energy-band gap (Eg) increased with increasing P doping [34]. The blue shift identified between the studied layers was also observed in theoretical and experimental previous works as a function of Mn and P doping [32,35,36]. Indeed, Yahyaoui et al highlighted the enhancement of Eg as a function of P doping in (Ga, Mn)(As, P) layers [37].…”

“…Interestingly, the Q r spectrum shows an extremum at the wavelength where Q i tends to zero, at 750 nm, 723 nm and 714 nm for the concentrations [P]=0%, [P]=8.8% and [P]=11.3%, respectively. The shape of Q i and Q r parts of the three layers reminds us of the expected behavior of the Kerr effect for a single oscillator optical transition [32]. One can notice that the Q i and Q r curves have a spectral behavior similar to the experimental Kerr rotation and ellipticity, respectively.…”

“…The MOKE measurements are performed in polar geometry in which the incident light beam was quasi-normal on the surface of the sample. Details of the experimental setup are found in [31,32]. The sample was illuminated with a monochromatic light from a 150 W Xe lamp.…”

Roadmap on topological photonics

“…The former approach will strongly benefit from novel etching and passivation techniques in AlGaAs and InGaAs-based materials, which already have the lowest linewidths. The latter approach could profit from the development of new materials like semiconductors weakly doped with magnetic impurities, like Mn, expected to produce larger Zeeman effects [127]. This dopant might however affect the polariton linewidths through the increase of the material absorption.…”