Anti-crossing of Landau levels of different two-dimensional subbands in GaAs in normal magnetic field

Tunnel current measurements between strongly disordered two-dimensional ele ctron systems in a perpendicular magnetic field are presented. Two-dimensio nal electron accumulation layers are formed by Si delta doping of GaAs on e ither sides of an AlGaAs tunnel barrier. Strong interaction between Landau levels of the two-dimensional subbands in each accumulation layers are obse rved as an anti-crossing of the related peak positions in the tunnel curren t versus voltage curves as a function of magnetic field. The splitting of t he interacting Landau levels is about 10 meV, which cannot be explained by non-parabolicity of the conduction band in GaAs. Possible reasons for the o bserved interaction are discussed. (C) 2001 Published by Elsevier Science B .V.