Single layer/bilayer transition of electron systems in AlGaAs/GaAs/AlGaAs quantum wells subject to in-plane magnetic fields

摘要

Equilibrium properties of electrons in double-heterojunctionAlGaAs/GaAs\AlGaAs structures are investigated theoretically, using a fullself-consistent numerical method. The transition from single to bilayerelectron systems is discussed for the case of double-junction structures withvarying distance between interfaces. In strong in-plane magnetic fields weobserved the same type of transition accompanied by large effects on the energyspectra. A new fenomenon in bilayer systems - separability of the energydispersion curve in parts corresponding to electrons either in first or secondlayer is analyzed in detail. The magnetic field induced variation in theeffective distance between electron layers is compared to the constant layersseparation in standard double-well structures. Due to relatively small and softelectrostatic barrier between interfaces we expect the van Hove singularity inthe 2D density of states to be easier detectable than in double-well systems.The cyclotron mass, proportional to the density of states and characterizingthe electron motion in tilted magnetic fields, is calculated as a function ofin-plane magnetic field. The separability of the energy spectra resulting intilted cyclotron orbits is demonstrated on a classical picture of an electronmoving in crossed electric and magnetic fields.