Interplay between electron spin and orbital pseudospin in double quantum dots

We investigate theoretically spin and orbital pseudospin magnetic properties of a molecular orbital in parabolic and elliptic double quantum dots (DQD's). In our many-body calculation we include intradot and interdot electron-electron interactions, in addition to the intradot exchange interaction of p orbitals. We find for parabolic DQD's that, except for the half or completely filled molecular orbital, spins in different dots are ferromagnetically coupled while orbital pseudospins are antiferromagnetically coupled. For elliptic DQD's spins and pseudospins are either ferromagnetically or antiferromagnetically coupled, depending on the number of electrons in the molecular orbital. We have determined orbital pseudospin quantum numbers for the ground states of elliptic DQD's. An experiment is suggested to test the interplay between orbital pseudospin and spin magnetism.