Electrostatic spin control in multi-barrier nanowires

We demonstrate that a consistent breakdown of the standard even-odd filling scheme in the Coulomb blockade regime can be easily obtained in a quantum dot containing two wells strongly coupled by a very transparent barrier. By exploiting a multi-gate configuration, we prove that a partial filling of nearly degenerate orbitals can be controlled electrostatically. Singlet-triplet spin transitions are demonstrated by low-temperature magneto-transport measurements.