Experimental observation of Landau levels in nonperiodic (Fibonacci) superlattices.

Abstract

Absorption spectra of GaAs/GaAlAs Fibonacci superlattices (FSL) with magnetic fields parallel to the layers show self-similarity at field values scaled by ${\mathrm{\ensuremath{\tau}}}^{2}$ [\ensuremath{\tau}=(1+ \ensuremath{\surd}5 )/2]. The one-dimensional nonperiodicity of the FSL affects the carrier motion perpendicular to the layers very differently from that parallel to the layers: In ${\mathit{B}}_{\mathrm{\ensuremath{\parallel}}}$, where carriers have to cross several barriers to complete a cyclotron orbit, clear Landau levels are observed, whereas in ${\mathit{B}}_{\mathrm{\ensuremath{\perp}}}$ the merging of the magnetic levels superimposed on the irregular eigenvalue spectrum of the FSL does not yield equally spaced spectra.