Landau-level crossing in two-subband systems in a tilted magnetic field

Abstract

We have studied the quantum Hall effect in parabolic ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ and square GaAs quantum wells with two occupied subbands in magnetic fields $B$ tilted by an angle $\ensuremath{\Theta}$ with respect to the normal to the sample. We built the density--magnetic field ${n}_{s}\text{\ensuremath{-}}B$ and angle-magnetic field $\ensuremath{\Theta}\text{\ensuremath{-}}B$ topological diagrams for the longitudinal resistivity ${\ensuremath{\rho}}_{xx}$ and observed that the latter shows a similarity with a simulation based on a single-particle harmonic potential approximation.