Quasi-periodic structure of Landau magnetic levels and absorption spectra of GaAs - (Ga,Al)As Fibonacci superlattices under in-plane magnetic fields

Abstract

A detailed theoretical study, in the effective-mass approximation, of the magnetic Landau subbands, wavefunctions, and intraband and interband absorption coefficients of quasi-periodic GaAs - (Ga,Al)As Fibonacci superlattices under in-plane magnetic fields is presented. Calculations are performed for in-plane magnetic fields related by and , with being the golden mean, and for magnetic fields appropriate for comparison with experimental measurements. It is shown that, for a given sample and in-plane magnetic field, the Landau magnetic subbands exhibit a Fibonacci-like quasi-periodic structure, and that these quasi- periodic properties are extremely useful in avoiding integration over the full range of cyclotron orbit centre positions. The intraband absorption spectra are calculated, at a given temperature, for n-doped GaAs - (Ga,Al)As Fibonacci superlattices under in-plane magnetic fields scaled by , and the theoretical absorption spectra are shown to be self-similar (for even n) and anti-self-similar (for odd n). For the interband magneto-absorption spectra of GaAs - (Ga,Al)As Fibonacci superlattices, we find a self-similar behaviour of the interband absorption spectra for magnetic fields scaled by , in agreement with available experimental data. The interband absorption coefficients are also evaluated for various in-plane magnetic fields with good overall agreement with experimental measurements.