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 well s. This theory is applicable to both the low and strong magnetic-field cases. The screened exchange interaction is calculated by using a gen eralized Thomas-Fermi screening model. The approximately linear increa se of the tunneling gap at low magnetic fields (B<9 T) and the switchi ng of the ground state between the tunneling-split first Landau levels are seen and explained as a result of the increasing of screening eff ects on the exchange interaction when both tunneling-split first Landa u levels are filled.