Effects of the screened exchange interaction on the tunneling and Landau gaps in double quantum wells

A self-consistent screened Hartree-Fock calculation, combined with the Landau quantization of in-plane electron motion, is performed to find the eigenstates and eigenenergies of electrons in double quantum wells. This theory is applicable to both the low and strong magnetic-field cases. The screened exchange interaction is calculated by using a generalized Thomas-Fermi screening model. The approximately linear increase of the tunneling gap at low magnetic fields (B<9 T) and the switching of the ground state between the tunneling-split first Landau levels are seen and explained as a result of the increase of screening effects on the exchange interaction when both tunneling-split first Landau levels are filled. © 1996 The American Physical Society.