Anisotropic exchange interaction in coupled semiconductor quantum dots

We obtain a microscopic description of the interaction between spins in semiconductors and in semiconductor quantum dots (QD's). It is based on a two-particle Kane Hamiltonian including Coulomb interactions treated by (k) over right arrow-(p) over right arrow expansion. This gives a third order term that has the form of an interaction between the spin of each electron and the orbital motion of the other. This interaction does not require inversion or Rashba asymmetries. It is proportional to the square of the band coupling and can be large for III-V compounds. We present detailed evaluations for spins in several QD's.