Electron-correlation effects in transport through a double-quantum-dot molecule

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Abstract
The effects of the electron correlation on the electronic structure and transport in a pair of vertically coupled quantum dots are studied as functions of the number of electrons and the distance between the two dots by using a numerical diagonalization method. The electron correlation drastically affects the spin structure of the ground states when the number of electrons and the distance between the dots are sufficiently large. The electronic states with the large (small) spin momentum are stable when the number of electrons is an odd (even) integer. A physical picture of this characteristic behavior can be understood by an analogy to that of the electronic states in the Hubbard model near half filling. The Coulomb oscillation can be seen in the conductance of the electric current through the double-quantum dots. When the distance between the dots is large, the amplitudes of several conductance peaks are suppressed by the electron correlation.